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FEBRUARY 1980 Volume 5, Number 2 $2.50 in USA/$ 




GRAPH THEORY 



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In The Oueue 



fi^TI February 1980 
Volume 5, Number 2 




Foreground 





page 72 








'■■—" 


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18 A FIRST LOOK AT GRAPH THEORY APPLICATIONS by Michael Ashbrook 
and Helmut Zinn 

If the use of graph theory raises a question, this article will supply an answer. The authors introduce the funda- 
mental concepts of graph theory and two methods of directed-graph storage. 

32 A COMPUTER-CONTROLLED WOOD STOVE by Steve Ciarcia 

Steve Ciarcia shows how he uses his computer to monitor and control a Hydrostove — a wood stove that heats 
water piped through it. 

72 A COMPUTER-CONTROLLED LIGHT DIMMER, Part 2: Implementation by 

John H Gibson 

Part 2 of this article shows how to construct the design that was presented in the January 1980 BYTE, using the 
Heathkit ET-3400 microprocessor trainer. 

92 IMPLEMENTING DYNAMIC DATA STRUCTURES WITH BASIC FILES by Ted 

Carter 

Using linked lists to maintain sorted files is one way to deal with limited memory, large files, and additions and 
deletions to these files. 

106 A FAST, MULTIBYTE BINARY TO BINARY-CODED-DECIMAL CONVERSION 
ROUTINE by Michael McQuade 

This general-purpose algorithm performs these conversions and assembler programs for the 8080 processor. 

192 A FINANCIAL ANALYSIS PROGRAM by John H Lehman 

Most investors will agree that financial stability and success require an organized systematic means of assessing 
investments. The program written by John Lehman can output the typical information required for such a financial 
report. 

202 ANOTHER PLOTTER TO TOY WITH, REVISITED: Design and Con- 
struction Details by Robert K Newcomb 

Robert Newcomb tells how to construct and program the low-cost plotting system described by Peter Lucas in the 
February 1979 BYTE. Robert uses a KIM-1 and various electromechanical parts. 



Background 



page 14 



58 SOLVING PROBLEMS INVOLVING VARIABLE TERRAIN, Part 1: A General 

Algorithm by Scott T Jones 

The method described by Scott Jones can be applied to a wide range of problems in business and industry as well 
as conflict simulations and games. 

116 A QUAD TERMINAL INTERFACE by Stephen A Alpert 

Building this interface solves the occasional problem of having one interface port and the need to use three or four 
peripherals. 

128 COMPARISON OF SOME HIGH-LEVEL LANGUAGES by Robert A Morris 

Some programming languages are more appropriate to a particular application than others. This comparison will 
help you choose the right language from the many possibilities. 

176 BASIC FORMATTED OUTPUT by William D Roch 

The feature provided here will give your BASIC package the control where a particular piece of information will 
appear on a line when you are performing input and output routines. 



Nucleus 



6 Editorial: The Seven Bridges of 
Konigsberg 

14 Letters 

69 BYTE News 

82, 86 Programming Quickies: Gasuse; 
String Comparator for Horizon 

88 Clubs and Newsletters 
140, 146, 172, 174 Technical Forum: 
Some Example Plots; Introduction to 
Code Tightening; Mining the Skip Chain 



for Extra Bytes of Code; Audio Meter for 
Your TRS-80; Algebraic Identities Are 
Not Numerical Identities 
154 Event Queue 
162, 208 BYTE's Bits 
168, 208 BYTE's Bugs 
188 Book Reviews 
212 What's New? 

255 Unclassified Ads 

256 Reader Service, BOMB 



February 1980 © BYTE Publications Inc 



Publishers 

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4 February 1980 © BYTE Publications lnc 




ON THE COVER 

Topology is the theme of this month's cover painting, "The 
Seven Bridges of Konigsberg" by Robert Tinney. It is a fanciful 
representation of a classical, topological problem made famous 
by the Swiss mathematician Enter, and it has a more than pass- 
ing resemblance to the works of the Sioiss artist M C Escher. 
The celebrated problem is discussed in detail by Carl Helmers in 
this month's editorial, and the painting is also loosely inspired 
by the theme article, "A First Look at Graph Theory Applica- 
tions." by Ashbrook and Zinn. Sharp-eyed readers might spot 
a visual reference to another famous mathematical problem 
hidden in the cover. 



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Editorial 



The Seven Bridges of Konigsberg 



by Carl Helmers 



Shugart 



Covers, like editorial themes, are sometimes drawn from interesting subjects 
intended as themes for an issue. But divergences can occur. This month, the 
nominal theme for the issue is the topic of graph theory. It takes only one 
article to suggest such a cover theme, and the article "A First Look at Graph 
Theory Applications " by Michael Ashbrook and Helmut Zinn provided the 
initial suggestion. But our actual cover is inspired by a historical problem in 
mathematics which led to the definition of a much broader field: topology. 

This generalization occurred as a result of trying to find a nice neat visual 
image that fits the topic of graph theory. In order to concoct a cover idea on 
graph theory, the first step is to start searching around for some theme on a 
diagram of nodes and interconnecting segments which is not some hackneyed 
abstract pun. In order to construct a visual image for a cover, I needed to find 
some seminal problem with dramatic visual import. This problem must define 
and suggest the general field of endeavor. So, I proceeded to hunt around. 

A good forest in which to hunt mathematical images is an excellent four- 
volume set of books entitled The World of Mathematics, by James R Newman, 
published by Simon and Schuster in 1956, and still available at a cost of 
$39.95. On the covers of the four volumes we find the description "a small 
library of the literature of mathematics, from A'h-mose the Scribe to Albert 
Einstein, presented with commentaries and notes." These books present a 
selection of original papers by mathematicians, with introductions and com- 
mentary by the editor. As serious or recreational reading for those interested 
in mathematical subjects, I highly recommend it. 

So, naturally, I turned to the index of Mr Newman's book. I knew that 
somewhere in that 2535-page work I might find some visual image with which 
artist Robert Tinney could work to create a cover. It did not take long to find 
the appropriate image. On pages 570 thru 599 we find Mr Newman's commen- 
tary on graph theory, which is really an illustrative subset of a much more 
general field, topology. Following three pages of editor's commentary, the two 
papers reproduced in this section of the book are Leonhard Euler's memoir 
"The Seven Bridges of Konigsberg" (1735) and a survey article "Topology," by 
Richard Courant and Herbert Robbins, taken from their book What Is Mathe- 
matics? (Oxford University Press, 1941). When I encountered the problem of 
the Seven Bridges of Konigsberg in the form of Euler's paper, I knew we had a 
cover image. 

The problem is quite simply stated: a city, Konigsberg, is built on an island 
in the river Pregel (see figure 1). We wish to find out if it is possible to cross all 
seven bridges in an afternoon's walk without crossing any bridge more than 
once. 



Figure 1: Map of the town of Konigsberg 

in Prussia, reproduced from 

Euler's paper on the subject, 

first published in 

1735. Within the 

town there is an 

island called 

Kneiphof, labeled 

A in the figure, around 

which flows the river 

Pregel. Seven bridges, labeled 

a, b, c, d, e, f, and g, cross the a 

two branches of the river. The various 

land areas of the town are labeled A, 

B, C, and D. 




6 February 1980 © BYTE Publications In 























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"When I was shopping around for my system, 
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BYTE February 1980 



What Euler did, in an eminently readable argument in 
his paper, is to prove that it is indeed not possible. He 
proves that the popular hobby of the Konigsberg folk of 
seeking that magic path could never succeed. In so doing, 
he helped to found the science of topology. According to 
Newman in his commentary on the paper, 

The problem — to cross the seven bridges in a 
continuous walk without recrossing any of them — 
was regarded as a small amusement of the Konigs- 
berg townsfolk. Euler, however, discovered an im- 
portant scientific principle concealed in the puzzle. 
He presented his simple and ingenious solution to the 
Russian Academy at St Petersburg in 1735. His 
method was to replace the land areas by points and 
the bridges by lines connecting these points. The 
points are called vertices; a vertex is called odd or 
even according as the number of lines leading from it 
are odd or even. The entire configuration is a graph; 
the problem of crossing the bridges reduces to that of 
traversing the graph with one continous sweep of the 
pencil without lifting it from the paper. If the graph 
contains more than two odd vertices, it may be 
traversed in one journey but it is not possible to 
return to the starting point. The general principle is 
that if the graph contains 2n odd vertices where n is 
any integer, it will require exactly n distinct journeys 
to traverse it. . . . 

Thus began a "vast and intricate theory 
[topologyl, " still young and growing, yet already one 
of the great forces of modern mathematics. 

Now we had the general outline of the image. Fine 
details remained to be worked out with Robert. Now, 
Robert Tinney and I know of a number of artists that we 
regard as extremely interesting in general style and sub- 
ject mater. There are, for example, the direct and con- 
scious influences of Maxfield Parrish and Norman 
Rockwell on Robert's style of painting as often seen in 
covers of BYTE. However, we have of late been getting 
immersed in the fascinating art of M C Escher. Part of 
this fascination has been lying dormant since Martin 
Gardner's series of articles on Escher and tesselations of 
the plane in Scientific American (see his "Mathematical 
Games" column in the July 1975 (page 112), August 1975 
(page 112), December 1975 (page 116), January 1977 
(page 110), and June 1978 (page 18) issues). The fascina- 
tion is of course greatly rekindled by the recent publica- 
tion of the book Godel, Escher, Bach by computer scien- 
tist Douglas R Hofstadter. 

So, given the theme of the seven bridges of Konigsberg, 
the added input of a recursive-programming computer- 
science pun clearly evident in the image, and a fascina- 
tion with Escher's style, Robert chose to produce a cover 
image inspired by the art of Escher. The result is what 
you see.B 

In Next Month's BYTE 

The March 1980 BYTE will be devoted to "Computers 
and the Sciences. " The theme articles will cover diverse 
topics such as "Electron Behavior in Chemical Bonds," 
"Electronic Planimetry, " "Chemistry Program for the 
Apple Computer, " and a "Derailleur Speed-Calculation 
Program. " 



An Update on Direct Cursor Addressing 
and UCSD Pascal 

In last month's editorial on the Apple Pascal system, 
I made some comments about difficulties in getting the 
UCSD System to emit the cursor addressing character 
of my Computer Peripherals Corp "COPS-10" ter- 
minal. This terminal requires the sequence of "control- 
P, <Y+32> , <X+32>" to directly address a given 
location on the screen. 

It turns out that the UCSD Pascal System (not just 
the Apple II version) gobbles "control-P" characters on 
output, whether through use of WRITE, WRITELN or 
even UNITWRITE. Naturally, it became a challenge to 
find out how to emit a controUP. 

So, trying brute force as a first method of solution, I 
wrote an assembly language program using the UCSD 
Pascal System's 6502 assembler. This assembly lan- 
guage program simply set up the parameter's for the 
routine "SHOUT" within the Apple II serial card's 
read-only memory, then called that routine to emit the 
control-P character. I proved it worked by writing a 
Pascal GOTOXY procedure and test program. 

The UCSD Assembler proved more than adequate 
for my purposes, in its 6502-oriented version running 
on the Apple. A most useful feature is its macro- 
instruction facility with conditional assembly. The 
Apple documentation of the UCSD System includes 
examples of assembly language interfaces which 
proved to be quite a helpful model. There was one 
convention that I had to worry about for a few 
assemblies. This was the fact that the assembler only 
allows hexadecimal integer constants. The assembler 
also demands uppercase only for tokens, although 
lowercase works fine in comments. 

Of course, the version of the Pascal GOTOXY that 
used this assembly language procedure had to have an 
external procedure definition. This presented no pro- 
blem when compiling without any special compiler op- 
tions. But the manual points out (and experience con- 
firms) that the "[$U— )" option must be active when 
compiling the code file that will be linked into the 
system by BINDER. Every time I try to compile with 
the required {$U— } compiler toggle, I get a Pascal syn- 
tax error §183, "External declaration not allowed at 
this nesting level. " This was in spite of the fact that the 
"PROCEDURE CTRLP3; EXTERNAL;" sequence is at 
the outer (PROGRAM) level of nesting. 

I tried everything I could think of: linking before 
BINDER, not linking, using it with the [$U] toggle and 
without, etc, etc. I even recalled the existence of a 
magical UCSD Pascal compiler toggle "{$T + \", which 
is required for compilation of super-large systems pro- 
grams. When used with the [$U~] option, I could get 
the program to compile and link with the assembly 
language program — but then BINDER would not ac- 
cept it. Clearly it was all to no avail. Would I be stuck 
with the GOTOXY cursor kludge of 

<home><LF>. . .<LF><HT>. . .<HT> 

forever? 



8 February 1980 © BYTE Publications Inc 



Circle 3 on inquiry card. 



At Intersystems, 
"dump" is an instruction. 

Not a way of life. 

[Or, when you're ready for IEEE S-KX), will your 
computer be ready for you?] 




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Ithaca Intersystems Inc., 

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Ithaca, NY 14850 

607-257-0190/TWX: 510 255 4346 




Well, impossible problems lead to new solutions 
when frustrations get high enough. One solution 
would of course be a new terminal that had the 
necessary cursor control keys (the up/down/left/right 
arrows) but used a different direct addressing se- 
quence. 

On the day I solved the problem, I was talking with 
Cameron Jones about getting the UCSD Pascal System 
version for my New England Digital Synclavier music 
synthesizer. (Cameron Jones, Syndey Alonzo, and Jon 
Appleton are the co-inventors of the Synclavier.) As 
the Synclavier and its ABLE/60 computer comes 
delivered, its native language is XPL. So implementing 
a UCSD Pascal system becomes a problem of imple- 
menting the core interpreter in XPL. 

As I was talking on the phone with Cameron, I final- 
ly realized what was wrong. The cursor addressing 
character of my terminal is an ASCII DLE character 
which is also known as control-P when emitted from a 
keyboard. And the UCSD System will always eat 
control-P characters, since this is the spaces- 
compression escape character of ".TEXT" files! 
Cameron pointed out that the specification of the 
UCSD Pascal UNITWRITE routine is that it will do 
spaces decompression. 

So I had to have a character that looks like a 
control-P to the terminal but not like a control-P to 
UCSD Pascal. This character is of course a character 
with the integer value 144. Its value is obtained by 
turning on the high-order bit in an 8-bit character by 
adding 128 to the control-P character code's value of 
16. While the Pascal program's character data value 
are 8 bits, the terminal only looks at the low-order 7 
bits. Thus, if the low-order looks like a control-P, 
turning on the high-order bit will keep Pascal from 
thinking it really is a DLE while allowing the terminal 
to think it is. 

Everything else immediately simplified and fell in 
place. Listing 1 shows the final version of the 
GOTOXY procedure, which now emits an 8-bit 



pseudo- control-P character that gets interpreted by 
the terminal as a 7-bit control-P character. 

Of course, by getting frustrated by this problem, I 
explored the use of assembly language features of the 
UCSD System. I learned how to link successfully to 
assembly language programs, use the macroassembler 
that comes with the system, and unwind parameters 
from the Pascal stack in assembly language programs. 
I will probably never again use an assembly language 
program with a Pascal program. But if I need to for 
some reason of speed, I now know it is possible. This 
short note and this month's editorial were the first 
texts I edited using the new version of GOTOXY; the 
results are quite an improvement — / am no longer 
limited by rather artificial delays required by last 
month's cursor addressing kludge. 

Listing 1: 

!»SU-«) 
PROGRAH GOXYi 

C the final version of the GOTOXY procedural used with Apple Pascal 

C and the Computer Peripherals Corporation COPS-10 terminal. The 

C ASCII (7 bit) seouencet 

C <ctrl P> <Y+32> <X+32> 

C causes direct cursor addressing > 

PROCEDURE FCOTOXY!x-a:<is»y_axist INTEGER)! 

( COPS 10 - GOTOXY J 

CONST 

eonlrol_P « 144 Chiah order bit on r but no effect 16+1203) 
VAR 

x.w : integer; 

abate 1 PACKED ARRBYCO. .0] OF CN6RI 



BEGIN 



! ... hou do we send a "control P" when the Pascal UNITURITE will ) 
C sobble it because it thinKs that it is spaces compression char- ) 
C acter? Uellf recodnlze that the terminal only pays atten- } 

C tion to 7 low order bits* Thus if we send a a control P with ) 
f the hiah order bit on» then UNITURITE will say "aha that is not 3 
( a control p" and the terminal will say "ah3 that is a control P" ) 
abyteCO] := CHR( Control-P ); 
UNITURITE! 1 >abyle.l.f 1 )i 



:: 1= >:_axis + 32; 
y := y-axis + 32; 
IF >: > ill THEN X := 111! 
IF ;: < 32 THEN >: 1= 32; 
IF y > 55 THEN y != S5; 
IF y < 32 THEN y 1= 32: 
abyteCO) := CHR(y); 
UNITURITE! l.abyte.l.tl 1! 
abyteCO) i= CHR< >:)! 
UNITURITE! lrabyle.lnl > 
END Csotoxy}! 



BEGIN (# DUMMY MAIN *) 

END. 

!*!U-*> 



Clll = 7? + 32) 



On Eclipses, Next Month's Editorial 
and the West Coast Computer Faire. . . 

As you read this February 1980 issue of BYTE, I will 
be embarking on a journey to make the technological 
fantasy of last July's editorial ("Computers and 
Eclipses," page 8) real. In the March 1980 editorial, I 
plan to describe some of the details of the computer 
system which will control my Nikon F2A camera in 
automatic photography of the 1980 solar eclipse from 
Kenya in Africa. 

I am scheduled to leave for Kenya on February 6, 
1980, joining a small expedition of solar physics 
experimenters organized by Norm Whyte of Monte 
Rio, California. Norm is performing experiments in- 
volving a custom designed camera under direct com- 
puter control of an Apple II. 

The only uncertainty is what the weather will be like 
at our observation site on the morning of February 16, 
1980. Whatever the weather, readers who are going to 
the West Coast Computer Faire in San Francisco in 
March 1980 will be able to see the results in a talk 



entitled "Microcomputers in Africa: A Travelogue of 
The 1980 Eclipse." 

Norm and I will be presenting this talk as part of the 
technical program. It will feature slides made during 
the trip showing the setup and equipment (as well as 
scenery) and — weather permitting — slides of the 
eclipse itself. . . .CH 

Articles Policy 

BYTE is continually seeking quality manuscripts written by indi- 
viduals who are applying personal computer systems, designing 
such systems, or who have knowledge which will prove useful to 
our readers. For a more formal description of procedures and 
requirements, potential authors should send a large (9 by 12 inch, 
30.5 by 22.8 cm), self-addressed envelope, with 28 cents US postage 
affixed, to BYTE Author's Guide, 70 Main St, Peterborough NH 
03458. 

Articles which are accepted are purchased with a rate of up to $50 
per magazine page, based on technical quality and suitability for 
BYTE's readership. Each month, the authors of the two leading 
articles in the reader poll (BYTE's Ongoing Monitor Box or 
"BOMB") are presented with bonus checks of $100 and $50. Unso- 
licited materials should be accompanied by full name and address, 
as well as return postage. 



10 February 1980 © BYTE Publications Inc 



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12 BYTE February 1980 



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BYTE February 1980 



13 



Letters 



8086 Software Needed 

I am interested in designing systems 
based on 8086 processors. Does anyone 
have some useful systems software to 
sell? I am particularly interested in file- 
handling software and operating systems 
in general. I am interested in purchasing 
source listings and I am prepared to visit 
software houses on my next trip to the 
US. 

Martin Healey 

Computer Systems Consultant 

9 Ennerdale Close 

Penylan, Cardiff CF2 5NZ 

GREAT BRITAIN 



Battle of the Buses 

In the October 1979 "BYTE News," 
page 107, Sol Libes contends, in an item 
about the S-100 bus, that "those who 
wish to have a machine capable of get- 



ting the maximum benefits of micropro- 
cessors must go the S-100 route." While 
Mr Libes was comparing the S-100 bus 
to all-in-one systems, such as the TRS-80 
and PET, his statement leaves out a 
number of computer systems with as 
much capability as S-100 systems, 
perhaps more in some cases. For exam- 
ple, the SwTPC S/09 and the Ohio 
Scientific Challenger III Series are two 
systems that come to mind. The former 
uses a 6809 processor with the SS-50 bus 
(see October BYTE, inside front cover), 
and the latter uses 6800, 6502, and Z80 
processors and apparently OSI's own 
bus (see back cover, same issue). Both of 
these systems have a 20-bit address bus 
for large memories. SwTPC and several 
other companies make SS-50 bus 
systems using the 6800. Other non-S-100 
bus systems include the Heath H8 and 
Hll. Any of these systems, and pro- 
bably others that I have left out, can be 
as good for serious personal computer 



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©1979 Ithaca Intersystems Inc. 



users as any S-100 bus computer. The 
S-100 bus is not the only possible route. 

Mr Libes also writes that "the S-100 
bus is not processor dependent." This 
statement is debatable, in spite of the ex- 
istence of S-100 boards for a number of 
microprocessors. Several signals on the 
S-100 bus are generated ONLY by the 
8080. Any other processor must be 
"bent" into generating (or responding to) 
these 8080-specific signals. 

Personal computing could use a truly 
processor-independent bus. I feel that 
the S-100 bus will not be totally satisfac- 
tory in this role. 

The mention of specific products in 
this letter does not necessarily constitute 
endorsement of these products. My 
point is simply that there are other buses 
besides the S-100, and that systems using 
these other buses can be just as capable 
as S-100 systems. 

Jim Howell 

5472 Playa Del Rey 

San Jose CA 95123 

Author Libes replies: 

Thank you for your letter regarding 
my comments on S-100 systems in the 
October BYTE News column. Despite 
the views expressed in your letter, I still 
stand by my view that "those who wish 
to have a machine capable of getting 
maximum benefits of microprocessors 
must go the S-100 route. " I agree with 
you that SS-50 and OSI Challenger 111 
systems offer more power than inte- 
grated systems such as the TRS-80, Ap- 
ple and PET. However, they still leave 
much to be desired compared to S-100. 1 
will explain shortly. 

Further, I also stand by my statement 
that "the S-100 bus is not processor 
dependent. " The fact is that presently 
there are manufacturers selling six dif- 
ferent 8-bit processor boards (8080, 
8085, Z80, 6502, 6800 and 6809) and 
five different 16-bit processor boards 
(9900, LSl-11, 8086, Z8000 and Pascal 
Microengine) for S-100 systems. This 
means that eleven microprocessors have 
already been interfaced to the S-100. I 
do not know of any other system with 
this processor independence. Many of 
these microprocessors could not even be 
interfaced to buses such as the SS-50 or 
OSI without sacrificing performance. 

When it comes to maximum power 
and flexibility the S-100 offers the 
following advantages over all other 
systems: 

• More software available. There are 
several times more languages, 
operating systems and applications 
packages for S-100 systems than for 
any other system. 



14 February 1980 © BYTE Publications Inc 



Circle 6 on inquiry card. 



WHY WE'RE NUMBER 





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January issue of BYTE, send $1.00 for 

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Circle 7 on inquiry card. 



BYTE February 1980 15 



• There are currently close to two 
dozen different manufacturers of 
S-100 mainframes and about fifty 
manufacturers of over 400 S-100 
plug-in boards. This is many times 
more than for any other system. 

• There is greater computer power 
capability with S-100. What other 
system has direct addressing of up to 
16 megabytes of memory (24 address 
lines) and 64 K input/output ports 
(16 address lines), up to eleven vec- 
tored interrupt lines, up to sixteen 
masters on the bus (with priority), up 
to twenty-three plug-in slots on the 
motherboard, up to 10 MHz clock on 
the bus, plug-in operator front panel, 
and more. 

• The S-100 bus is now standardized by 
the Institute of Electrical and Elec- 
tronic Engineers (IEEE) assuring con- 
formance among manufacturers. 

Regarding your reference to the H8 
bus, note that Heath has discontinued 
production of this unit. Besides, it was 
dedicated exclusively to the 8080 and 
therefore was destined to an early death. 
The Heath Hll is essentially the same 
as and uses the same bus specifications 
as a Digital Equipment Corp LSTll. Few 
other firms support the LSTll with pro- 
ducts within the price range of the 



typical hobbyist. The hardware and soft- 
ware facilities, compared to the S-100, 
are limited and expensive. 

Again, thank you for reading my col- 
umn and I welcome any further com- 
ments you wish to make regarding my 
opinions. 

Sol Libes 



Pi in the Sky 

As I get older, I forget more and more 
often that the "tricks" I sometimes use 
may not be common knowledge. I have 
recently come across several short pro- 
grams that evaluate % to five or six 
decimal places. These are good pro- 
grams, and I salute their authors. I, 
however, use the shortest of all pro- 
grams for it and would like to pass it 
on. It gives an approximate answer that 
is in error by 27 parts in 100 million. 
Since this is well within the allowable . 
error of most computers, I use it without 
hesitation in all computer programming 
expressions. 

Here goes. To enter ir accurate to six 
decimal places, write in its place 
1/(113/355). That's all there is to it! The 
value of that expression is 3.14159292, 
while 7T is 3.14159265 .... 




This little gem was taught to me for 
use on the slide rule, back during the 
1940s. I pulled it out of my memoirs 
recently when I got my first microcom- 
puter. 

Please note that the denominator is 
easily remembered as the first three odd 
integers, doubled. The order of their ap- 
pearance is obvious. 

Emory W Sprenkle Jr 
POB 542 (53 Allen Rd) 
Billerica MA 01821 



Keep Telling It Like It Is . . . 

Thank you for the November editorial 
regarding pseudoscience and biorhythms 
in particular. It was certainly refreshing 
to have a hobbyist magazine of BYTE's 
reputation so clearly delineate be- 
tween harmless biorhythm algorithms 
for the sake of computing recreation and 
the unscientific foundations of 
biorhythmic theory. Too many sup- 
posedly educated and intelligent people 
seem to have fallen into the "computer 
generated, therefore true . . ." trap you 
described. Perhaps you have caused 
some of them to critically examine the 
unsupportable premises of biorhythmic 
theory. Now if I could just get the cam- 
pus radio station to stop broadcasting 
horoscopes . . . 

Thomas Dolash 
Assistant Professor of Physics 
Physics and Engineering Dept 
Vincennes University 
Vincennes IN 47591 



Good Humor Needed 

I have found your magazine to be 
very educational and of excellent 
quality. I look forward to getting the 
new issue each month. However, I have 
a suggestion that I think might make 
your magazine even better and would be 
enjoyed by all your readers. Why not 
add a "Jokes & Riddles" column and a 
comic strip or two, and maybe a few 
"one-framers"7 I realize that your 
magazine tries to present a serious ap- 
proach, but I think that this addition 
would be a plus, and a bit of humor 
would make it more fun for everyone. 
So how about it? 

William P Carlson 

Rosewood Cir 

North Syracuse NY 13212 

You would not believe the number of 
unsolicited cartoons we get that are an- 
chored in the dark ages of computing 
prior to personal computing. 

The problem is finding cartoon and 
humor generators who also understand 
the current era in computing. . . .CH ■ 



16 February 1980 © BYTE Publications Inc 



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BYTE February 1980 17 



A First Look at 
Graph Theory Applications 



What do the following problems 
have in common? 

• Finding the shortest route between 
two particular cities on a compli- 
cated road map. 

• Finding the shortest route between 
any two cities on a road map. 

• Selecting a set of roads that con- 
nects all the cities on your map and 
has less total mileage than any 
other such set. 

• Calculating the maximum amount 
of liquid that can flow through a 
system of interconnected pipelines 
per unit of time. 

These four real-life problems can 
be interpreted in terms of graph 
theory and can be solved by 
remarkably simple and efficient pro- 
grams. The problems belong to a 
much larger category of operations- 
research problems; these were 
selected as examples because of their 
comparative simplicity. Algorithms 
for solving such problems along with 
the necessary background for under- 
standing them will be examined. 

While our terminology follows that 
of Narsingh Deo, our programs are 
quite different from his. If you 
become interested in solving more 
graph-theoretic problems on your 
own, you will find his book a stimu- 
lating introduction. (See Graph 
Theory with Applications to 



Michael Ashbrook 

Helmut Zinn 

Wilhelm Epstein Str 27 

6000 Frankfurt am Main 50 

WEST GERMANY (BRD) 

Engineering and Computer Science 
by Narsingh Deo, Prentice-Hall, Inc, 
1974.) 

Fundamental Technology 
and Concepts 

A graph consists of a set of vertices 
(singular: vertex) and a set of edges 
that connect the vertices. In the 
previous examples the cities are the 
vertices and the roads are the edges. 
In drawings and diagrams the vertices 
of a graph are shown as dots or as 
tiny circles; the edges are shown as 
lines. A vertex and an edge are said to 
be incident if they touch. This rela- 
tion of being incident holds the graph 
together. 

A digraph (short for directed 
graph) consists of a set of vertices and 
a set of directed edges. Real-life 
examples of digraphs include systems 
of canals in which the water flows 
from point to point only in the 
downhill direction, electric networks 
in which the current flows only in one 
direction, and systems of one-way 
streets. The vertex from which a 
directed edge starts is called the initial 
vertex of the edge; that would be the 
point at the higher end of a canal. The 
vertex at which a directed edge ends is 
called the terminal vertex of the edge; 
that would be the point at the lower 
end of the canal. 

Remember that each edge is inci- 
dent (touches) with exactly two ver- 



tices, therefore every directed edge 
has exactly one initial and exactly one 
terminal vertex. A vertex can be inci- 
dent with several directed edges, 
therefore the same vertex can be the 
initial vertex of one edge and the ter- 
minal vertex of another edge. See 
figure 1 for an example of a digraph. 

Unless explicitly stated, all graphs 
and digraphs that are discussed are in 
one piece. That is to say, that for any 
two vertices there is at least one way 
to travel back and forth between 
them along the edges of the graph. 
Graphs (both directed and undir- 
ected) with this property are said to 
be connected. Disconnected digraphs 
are not discussed in this context 
because they can be treated as a set of 
connected digraphs. 

For a similar reason, this article 
will concentrate on digraphs. A graph 
can usually be replaced by a digraph 
with the same set of vertices and 
exactly two directed edges, going in 
opposite directions, for every 
undirected edge of the original graph. 

There are many ways to represent a 
digraph in a computer. Each method 



About the Authors 

Michael Ashbrook became interested in 
operations research after first studying 
mathematics. Helmut Zinn became involved 
with small computers through his work in elec- 
tron]echanical engineering. Both collaborate at 
the Technische Hochschule in Darmstadt. 



18 February 1980 © BYTE Publications Inc 



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Figure 1: Example of a digraph (directed graph) 
directed edges. 



that has seven vertices and twelve 



has its advantages and its drawbacks; 
each has its applications. The two 
basic methods used to encode a 
digraph will now be discussed. 

A Matrix Called DIGRAPH 

Consider a digraph containing a 
certain number of vertices n r . The n, 
vertices of this digraph are repre- 
sented by the natural numbers from 
1 to n v . The edges of the digraph are 
represented by the entries of an n v by 
h„ matrix called DIGRAPH. If the 
digraph has a directed edge from the 
vertex j to the vertex /, then the entry 



DIGRAPHS /) of matrix DIGRAPH 
that is in the i-th row and the ;'-th 
column has a nonzero value, 
DIGRAPHS ;)*0. If there is no edge 
from vertex i to vertex ;', the matrix 
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The matrix DIGRAPH can be used 
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represent the distance from city i to 
city ;'. If you need to store no more 
data about an edge than the two ver- 
tices i, j which it connects, then the 



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A directed graph (digraph) 
consists of a set of vertices 
and a set of directed edges. 

hi ii i mi in i in i ii mi mi mi ii ii i hi imiiii minium inn mum 

presence of the edge in the digraph is 
usually indicated by setting 
DIGRAPHS /) = l. 

The matrix DIGRAPH is best 
suited for small-scale applications 
which involve no more than roughly 
fifty vertices. A digraph with n„ ver- 
tices, can be stored as a matrix that 
requires (n v ) 2 storage locations. 

Disadvantages of 
Matrix Storage 

In large-scale applications involv- 
ing several hundred vertices, the 
matrix DIGRAPH often becomes 
sparse (or sparsely populated). The 
proportion of entries that are equal to 
zero increases. This happens because 
the real-life structures that are being 
stored as digraphs have relatively few 
edges compared to the number of 
edges which they could have. 

Every town in the United States 
could be connected with all of the 
other towns by a direct road. As a 
practical matter, however, any given 
town is linked directly to only a few 
neighboring communities. Therefore, 
the DIGRAPH matrix of the total 
road system consists almost entirely 
of zeroes that mean nothing but the 
absence of a direct road between most 
combinations of two given towns. 
This matrix is very large and cannot 
be stored efficiently. 

Increasing Storage Efficiency 

In order to solve large-scale 
problems using a limited amount of 
storage space, a more efficient way of 
storing digraphs is necessary. Space 
should not be wasted on 0s that repre- 
sent nonexistent edges. 

As before, the n, vertices of the 
digraph are represented by the 
numbers 1 to n v . The edges are listed 
as pairs of numbers; the edge from 
vertex i to vertex ; is shown as the 
pair (/, /). 

Suppose the digraph has a certain 
number of edges, n c , then these edges 
can be expressed as an n e -by-2 array 
called EDGE. Each row (i, /) of the 
EDGE array specifies one edge; the 
first entry i stands for the edge's 
initial vertex i, and the second entry j 
stands for the terminal vertex ;' of the 



20 February 1980 © BYTE Publications lnc 



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BYTE February 1980 21 




VERTEX 



EDGE 



2 u- u- 



POINTER 




» END OF CHAIN 



END OF CHAIN 



Figure 2: Portion of a digraph as 
represented by the list-oriented data struc- 
ture. The arrows connecting the entries in 
the three lists {2-hy-2 arrays) show the 
logical connections in storage that repre- 
sent the structure of the digraph. The 
arrows can be read as "points to." 

In the list EDGE, after the identification 
number of the edge, two numbers that 
specify the initial and terminal vertices of 
that edge are found. For example, edge 3 
has initial vertex 30 and terminal vertex 
34. 

In the list POINTER, each edge number 
has associated with it two other numbers 
that refer to positions of edges in the list 
EDGE (not in the digraph itself). The ini- 
tial pointer of an edge refers to the last 
edge preceding the current edge that has 
the same initial vertex as the current edge. 
For example, the fourth entry in the 
POINTER list shown here points to the 
entry 3 in the EDGE list, showing that 
edge 4 has the same initial vertex as edge 
3. The terminal pointer of an edge refers 
to the last edge preceding the current edge 
that has the same terminal vertex as the 
current edge. 

In the list VERTEX, for each vertex in 
the digraph, there is an entry that tells the 
number of the last row of EDGE in which 
the current vertex appears as the initial 
vertex. There is also an entry that tells the 
number of the last row in the EDGE list in 
which the current vertex appears as a ter- 
minal vertex. For example, observe that 
the last edge with initial vertex 30 is edge 
5; the last edge in EDGE with terminal 
vertex 30 is edge 2. 



edge. If there is more information to 
be stored concerning the edges, then 
columns can be added to EDGE. 

For the sparse digraphs that are 
being considered, the amount of 
storage space needed for EDGE is /c??„ 
rather than n v 2 ; where k is the average 
number of edges per vertex in a given 
digraph. 

The price for this significant saving 
in space is an increase in access time. 
To find all the edges incident with a 
vertex i in DIGRAPH, simply scan 
the ;'-th row and the ;'-th column of 
DIGRAPH. To find all the edges inci- 
dent with vertex ; in EDGE, scanning 
the entire list is necessary. Since all of 



the programs rely heavily on finding 
the edges that are incident with a 
given vertex, it pays to trade a little 
storage space for a reduction in access 
time. 

To cut down on the access time, 
add a column of initial pointers and a 
column of terminal pointers to 
EDGE. You can spare yourself need- 
less confusion if you always remem- 
ber that these pointers refer to the 
positions of edges in the list EDGE 
and not in the digraph itself. 

The initial pointer of a particular 
edge (i, j) refers to the last edge 
preceding the current edge (i, j) in 
EDGE that has the same initial vertex 



i as (/, /), If (;', ;') is the first edge in 
EDGE that has the initial vertex i, 
then the initial pointer of (;', /) has the 
value zero. 

The terminal pointer refers to the 
last edge preceding (£, /) in EDGE 
which has the same terminal vertex / 
as (t, /). If (/', /) is the first edge in 
EDGE with the terminal vertex /, then 
its terminal pointer has the value 
zero. 

In order to reduce the access time 
further, establish a list called 
VERTEX in the form of a 2-by-n, 
array. The i-th row of VERTEX 
stands for the z'-th vertex of the 
digraph. The value of VERTEX(i, 1) is 
the number of the last row of EDGE 
in which i appears as the initial 
vertex. The value of VERTEX(i, 2) is 
the number of the last row in EDGE 
in which i appears as a terminal 
vertex. 



22 February 1980 © BYTE Publications Inc 



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BYTE February 1980 23 




30 40 50 60 70 80 90 100 
slUMBER OF VERTICES (n u ) 



Figure 3: Graph showing storage space requirements (st) of a digraph plotted as a func- 
tion st(nj of the number of vertices (nj in a given digraph. It should be assumed that 
four bytes are required to store a decimal number. 

The upper curve (black) shows the function st(nj when you use the method of storing 
your digraph representation in the matrix DIGRAPH. 

Storage requirements of the list-oriented storage scheme vary according to the 
number of edges (nj. The equation is st(n„,n e ) = 2n v + 4n e . If the digraph has some con- 
stant k times as many edges as it has vertices (represented by the equation 
n, : = knj, then the equation of storage space becomes 

st(nj = 2n„ + 4kn v = (4k + 2)n„ 

The curve for the case k—3is shown in red (when there are three times as many edges as 
vertices), and the curve for k = 5 is shown in blue. 

One fact illustrated by this diagram is that the list-storage approach is more efficient 
in use of storage space than the matrix approach so long as the digraph being stored has 
few edges compared to the number of edges that it could have (a sparsely populated lor 
just sparse] digraph). In terms of the equations here, sparseness means that k is much 
smaller than n v . The list-oriented storage method becomes relatively more efficient than 
matrix storage as digraphs become more sparse. 



Listing 1: The digraph input and concatenation program in BASIC. This program was 
developed on an Exidy Sorcerer computer system. 



Real-life structures pro- 
duce digraphs that have 
relatively few edges. 
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii 

The list-oriented digraph represen- 
tation is illustrated in figure 2. 

Searching the Lists 

Suppose you want to find those 
edges that have i as their initial 
vertex. Look at VERTEX(/, 1); if its 
value is zero, there are no such edges 
in the digraph. If its value is some 
nonzero value x, the first such edge is 
found in the Jt-th row of EDGE. If the 
value of the edge's initial pointer, 
PTR(x, 1), is zero, there are no more 
such edges in the digraph. (POINTER 
is a reserved word in our BASIC inter- 
preter, so we have to use the abbre- 
viation PTR.) If PTR(x, 1) equals 
some nonzero value y , the next such 
edge is found in the y-th row of EDGE 
and the new pointer ,is found in 
PTR(y, 1). 

Continue to follow the pointers 
from edge to edge until a pointer with 
the value zero is found, which tells 
you that you have now found all the 
edges that have i as their initial 
vertex. If you substitute the value 2 
wherever 1 occurs in the preceding 
paragraph, then there is an adequate 
explanation of the systematic search 
for all edges that have i as their ter- 
minal vertex. 

The same scheme that has been 



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320 
330 
340 
350 
360 
370 
380 
390 
400 
410 
420 
430 
440 
450 
460 
470 
480 
490 



DIGRAPH INPUT AND CONCATENATION 

COPYRIGHT 79/4 BY 

MICHAEL ASHBROOK & HELMUT ZINN 

FRANKFURT AM MAIN 



REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM *■««""*••""*........»........■....<.......*«. 

REM READ AND LINK EDGE LIST 

INPUT "NUMBER OF VERTICES"; NV 

INPUT "NUMBER OF EDGES "; NE 

DIM VERTEX(NV, 2) 

REM VERTEX(V, 1) = EDGE WITH V AS INITIAL VERTEX 

REM VERTEX(V, 2) = EDGE WITH V AS TERMINAL VERTEX 

DIM EDGE(NE, 2), PTR(NE, 2) 

REM EDGE(E, 1) = INITIAL VERTEX OF EDGE E 

REM EDGE(E, 2) = TERMINAL VERTEX OF EDGE E 

REM PTR(E, 1) = NEXT EDGE WITH THE SAME INITIAL VERTEX 

REM PTR(E, 2) = NEXT EDGE WITH THE SAME TERMINAL VERTEX 

FOR E = 1 TO NE 

PRINT E; "EDGE (INITIAL VERTEX, TERMINAL VERTEX) "; 

INPUT EDGE(E, 1), EDGE(E, 2) 

NEXT E 

REM SETTING UP THE POINTERS 

REM L = 1 IMPLIES INITIAL POINTER OR VERTEX 

REM L =2 IMPLIES TERMINAL POINTER OR VERTEX 

FOR L = 1 TO 2 

FOR E = 1 TO NE 

V = EDGE(E, L) 

IF VERTEX(V, L)=0THEN PTR(E, L) = 0: GOTO 330 

PTR(E, L) = VERTEX(V, L) 

VERTEX(V, L) = E 

NEXT E 

NEXT L 

PRINT 

PRINT " VERTEX LIST"; 

PRINT TAB(20); "EDGE LIST"; 

PRINT TAB(40); "POINTER LIST" 

N = NV: IF NV<NE THEN N = NE 

FOR I = 1 TO N 

IF I>NV THEN GOTO 440 

PRINT I;VERTEX(I, 1);VERTEX(I, 2); 

IF I>NE THEN GOTO 470 

PRINT TAB(20);I;EDGE(I, 1);EDGE(I, 2); 

PRINT TAB(40);I;PTR(I, 1);PRT(I, 2); 

PRINT 

NEXT I 

END 



24 February 1980 © BYTE Publications Inc 




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BYTE February 1980 25 



Listing 2: A sample execution of the program of listing 1 using data from figure 1. An 
interpretation of the output is given in figure 2. 



RUN 

NUMBER 

NUMBER 

1 EDGE 

2 EDGE 

3 EDGE 

4 EDGE 

5 EDGE 

6 EDGE 

7 EDGE 

8 EDGE 

9 EDGE 

10 EDGE 

11 EDGE 

12 EDGE 



OF VERTICES? 7 
OF EDGES ? 12 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 
(INITIAL VERTEX, 



TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 
TERMINAL 



VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 
VERTEX) 



1,2 
1,3 
2,3 
2,4 
2,5 
3,2 
3,4 
4,6 
5,4 
5,7 
6,3 
6,7 



VERTEX LIST 

1 2 

2 5 6 

3 7 11 

4 8 9 

5 10 5 

6 12 8 

7 12 



EDGE LIST 



2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 



POINTER LIST 


1 








2 


1 





3 





2 


4 


3 





5 


4 





6 





1 


7 


6 


4 


8 








9 





7 


10 


9 





11 





3 


12 


11 


10 



READY 



START (LINE 100) 



INPUT NUMBER OF VERTICES (NV) (LINE 110) 
NUMBER OF EDGES (NE) 



DECLARE VARIABLE Dl MENSIONS ( LINE 130) 
VERTEX (NV,2) 
EDGE (NE,2) 
PTR (NE.2) 



INPUT EDGE SPECIFICATIONS (LINE 210) 

(INITIAL VERTEX, TERMINAL VERTEX) 



DO WHILE L VARIES FROM 1 TO 2 (LINE 250) 
LINK INITIAL POINTERS (L=l) AND 
LINKTERMINAL POINTERS (L=2) 



V = EDGE IE.L) 

V -- INITIAL OR TERMINAL VERTEX OF EDGE E 



IF VERTEX (f.Ll'O (LINE 310) 




SET POINTER TO 
CHAIN END 



PTR (E,L I = 



SET POINTER TO THE 
NEXT PREVIOUS EDGE 
WITH THE SAME INITIAL 
(OR TERMINAL) VERTEX 
PTR <E,L I ' VERTEX IV,L I 



VERTEX !V,L) = E 

CONCATENATE EDGE WITH VERTEX LIST 



UNTIL E = NE (FOR ALL EDGES FROM 1 TO NE ) 



OUTPUT VERTEX, EDGE, PTR (PRINT ALL LISTSMLINE 360) 



STOP (LINE 490) 



Figure 4: A Nassi-Schneiderman chart showing the algorithm used by the BASIC pro- 
gram of listing 1. Nassi-Schneiderman charts are a system of stylized flowcharts that are 
designed for use with structured programming techniques. The chart is read from top to 
bottom. Line numbers refer to lines in the BASIC program in listing 1. 



introduced to store digraphs can be 
used for storing undirected graphs by 
ignoring the distinction between 
initial and terminal vertices and 
pointers. In the case of undirected 
graphs, a single pointer would serve 
as well as two pointers and occupy 
less storage space. If you are enter- 
prising, you can work out the details 
of this variation and write the appro- 
priate program yourself. Figure 3 
compares storage requirements. 

Generating Lists Under 
Program Control 

Have you wondered why the lists 
have been searched from bottom to 
top and why the pointers are linked 
backwards? By doing so, you can 
simplify the task of generating the 
pointer lists. 

The Nassi-Schneiderman chart 
given in figure 4 shows the logic 
followed by the BASIC program of 
listing 1. Here is some additional 
explanation. Numerals refer to line 
numbers in listing 1. 

300 Assume that you are linking the 
initial pointers (with L = l). The 
initial vertex of edge E is stored 
in V. 

310 If the vertex number V has not 
been recorded as an initial 
vertex up to now, you have 
found the end of its chain of ini- 
tial pointers. Skip line 320 
because there is no previous 
pointer to link up with. 

320 If V has been previously record- 
ed as an initial vertex, get the 
location of its earlier occurrence 
in EDGE from VERTEX and set 
the initial pointer PTR(E, 1) of 
edge E to point to this location. 

330 Record the location E of V in list 
EDGE in VERTEX(V, L). This is 
the lowest location of V in 
EDGE that is known at this 
time. If V occurs again as an ini- 
tial vertex further down in 
EDGE, this lower location will 
be recorded. 

Graph Applications 

Some obvious examples of graphs 
and digraphs that occur in the real 
world have been mentioned: com- 
munication and transportation net- 
works. There are more abstract 
systems that also have an undirected 
or directed graph structure. 

Complicated projects consisting of 



26 February 1980 © BYTE Publications Inc 




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thousands of interdependent tasks are 
often planned with the aid of graph- 
theoretic methods. The tasks can be 
considered as the vertices of a 
digraph; their interdependencies can 
be expressed as directed edges. 

This approach allows managers to 
visualize the problems about which 
they must make decisions, and gives 
the managers the opportunity to 
delegate routine work to the com- 
puter. The maximum and minimum 
times for project completion and the 
effects of delays upon parts of the 
project or upon the whole project can 
be calculated by simple software 
routines. 

The first large-scale project to 



which these methods were successful- 
ly applied was the development of the 
Polaris missile system. Today, use of 
project networks is a standard 
management technique. 

If you are interested in applying 
graph theory to the social sciences, 
you should read Structured Models: 
An Introduction to the Theory of 
Directed Graphs by Harary, Nor- 
man, and Cartwright. 

Closing Observation 

This article cannot end without 
observing that almost all users of 
computers are intimately familiar 
with one form of directed graph, the 
flowchart. ■ 



REFERENCES 

Aho, A V, J E Hopcraft, and J D Ullman. 
The Design and Analysis of Computer 
Algorithms. Addison-Wesley Publishing 
Co, Reading, MA, 1974. 
Christofides, N. Graph Theory: An Algo- 
rithmic Approach. Academic Press, New 
York, 1975. 

Deo, N. Graph Theory with Applications to 
Engineering and Computer Science. 
Prentice-Hall Inc, Englewood Cliffs, NJ, 
1974. 

Harary, F, R Z Norman, and D Cartwright 
Structural Models: An Introduction to the 
Theory of Directed Graphs. John Wiley 
and Sons Inc, New York, 1965. 
Ore, O. "Theory of Graphs," Colloquium 
Publications of the American Mathemati- 
cal Society, American Mathematical 
Society, Providence, Rl, volume 38, 1962. 



28 February I9S0 © BYTE Publications Inc 



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BYTE February 1980 29 




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30 BYTE February 1980 




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Gispcis's Circuit Gellsp 

Copyright © 1980 by Steven A Ciarcia. All rights reserved. 



A Computer-Controlled 
Wood Stove 



Steve Ciarcia 

POB 582 

Glastonbury CT 06033 



"Come inside, Roger, and get out 
of the cold." I held my kitchen door 
ajar as he crossed the front yard 
towards me. Great clouds of leaves 
blown by the cold wind furiously 
encircled him. The landscape was 
stark and gray, and all weather in- 
dicators pointed toward an impen- 
ding snowstorm. 

Roger, a local electrician, had come 
by to discuss some electrical work I 
needed done on a new garage I was 
building. As he stepped through the 
doorway he remarked, "Sure looks 
like snow. Have you got enough gas 
for your Jeep in case you need to 
plow yourself out of this wilderness?" 

Roger's remark reminded me that 
the terms "picturesque" and "remote" 
are often synonymous when describ- 
ing a home in Connecticut. The only 
place I had been able to buy a house 
with more than half an acre of land 
was 25 miles from civilization. And 
while Roger's controlled, old Yankee 
humor prevented him from laughing 
out loud as he spoke, the thought of 
me, basically a kid from the city, 
independently plowing my 300 yards 
of driveway seemed to produce a 
slow-forming look of amusement. 

The Jeep he was referring to was 
about 20 years old and was used only 
for plowing. I rather enjoyed the 
straightfoward task of rearranging 
snow with it. A certain spirit of ex- 
citement came over me each time I 
stepped into the driver's seat and 



asked myself the all-important ques- 
tion posed by every adventurer: "I 
wonder if this heap will start?" 

My neighbor, who shares the chore 
of plowing, thought I was a sissy 
when I finally added lights to the Jeep 
for night driving. Somehow, not see- 
ing the rocks makes hitting them 




Photo 1: The Hydrostove is installed in 
the corner of the Circuit Cellar. Take note 
of the two copper pipes coming out the 
rear of the stove into the wall. The pipes, 
which are buried behind the wall and 
above the ceiling, go to the furnace, which 
is 35 feet away. 



more fun for him. I never did ask him 
how he had broken the driveshaft the 
previous year. 

I continued my masochistic 
thoughts of the Jeep. "It should be 
okay," I said, "but frankly, if it 
breaks down, I think I'll just hiber- 
nate in the cellar for the winter." 

Roger still had not taken his coat 
off as he added, "You might expect to 
enjoy such an arrangement, but I 
think you will find that you need out- 
side services more than you think." 

"Give me an example." 

Roger uncomfortably shrugged his 
shoulders. Something other than the 
conversation was bothering him. 

"Oil is a good example. You heat 
with oil, right? How do you propose 
to fill your oil tank if the truck can't 
get down the driveway? I'll bet this 
glass barn you have here almost re- 
quires a direct pipeline to the 
refinery." 

I did not exactly relish having my 
contemporary home called a glass 
barn but there was some merit to his 
statement. I retorted, "Who needs..." 

Roger interrupted me in mid-state- 
ment. "Speaking of heat... what are 
you running here, a sauna?" 

'Take your coat off, Roger. Maybe 
then you won't be so hot. I'm not so 
sure you even need both the wool 
shirt and sweater you have on." 

Tossing his coat across to the 
nearest chair and tugging on his 
sweater, he continued. "Whenever I 



32 February 1980 © BYTE Publications Inc 



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BYTE February 1980 33 




Photo 2: Logs up to 24 inches in length are 
placed in a grate which consists of water- 
filled tubes. 

visit anyone during the winter I 
presume their house is at 60 degrees 
like mine. It must be 12 degrees out- 
side, and..." he walked over to the 
thermostat, "according to this it's 75 
degrees in here!" 

"I don't usually have it this warm, I 
was just testing the heating system 
now that it's computer-controlled." 

"What's there to control? Turn the 
oil burner on longer and it gets hot- 
ter." 



"Who said anything about an oil 
burner?" 

"Electric heat is even worse!" he 
quickly added. 

"We have oil heat... but it hasn't 
been on for two days. All I have now 
is one wood stove." 

Roger's momentary blank stare and 
open mouth were instantly replaced 
with a look of disbelief. Standing 
there by the thermostat he quickly 
scanned the room. With extreme 
skepticism he replied, "What are you 
handing me? A twelve-hundred- 
square-foot room, twelve-foot ceil- 
ing, three hundred square feet of glass 
and seventy-five degrees? I don't see 
any stove!" Roger walked over to a 
hot-air duct near one of the windows, 
stooping down and holding his open 
palm over the opening he exclaimed, 
"Wood stove, phooie! There's hot air 
coming out of this duct. You have the 
oil burner on!" 

"No, Roger. I have a wood stove 
down in the Circuit Cellar that is 
plumbed directly into the central 
heating system." 

"A wood stove? In a hot-air 
heating system?" 

"Well actually, Roger, my heating 
system is both hot water and hot air, 
and the wood stove heats water. It's 
called a hydronic wood stove." 

"What the heck is a hydronic wood 
stove?" 

Roger was definitely at a loss for 
words. I put my hand on his shoulder 




Photo 3: In operation, the heat from the fire warms the water in the tubes. This is a 
relatively small fire. The fire box is usually filled. 



and said, "Think of it as Yankee 
ingenuity. Come on downstairs and 
I'll explain how it works." 

A Hydronic Wood Stove 

A hydronic wood stove is just what 
the name implies. It is a wood stove 
that heats water. The particular wood 
stove that I have is trade-named 
Hydrostove and it is made by Hydro- 
Heat Division, Ridgeway Steel, POB 
382, Ridgeway PA 15853. Photo 1 
shows it installed in the corner of the 
Circuit Cellar. 

The Hydrostove looks like an 
ordinary wood stove. It is con- 
structed of cast iron and weighs about 
400 pounds. The difference between it 
and a regular wood stove is in the 
method of heat removal from the 
burning wood and the ability to chan- 
nel the energy output into the central 
heating system. 

A regular wood stove produces 
only radiant energy and is generally a 
one-room heater unless fans or con- 
vection registers are employed to 
spread the heat around. The surface 
temperature of such stoves can 
approach the temperature of the 
burning wood itself, and great care 
must be taken to keep combustible 
material more than 4 feet away. 

Typical wood-stove operation is to 
put in a full load of wood, get it good 
and hot (warming up the room to 
around 75° F), and then close the 
dampers to reduce the heat output. 
This is the only way to keep the room 
from becoming unbearably hot. An 
unfortunate byproduct of this process 
is that a slow, smoldering fire creates 
creosote buildup in the chimney. 
Since only the area directly around 
the stove is heated, it is likely that an 
adjacent room will be terribly cold 
unless fans are used to blow the heat 
around. 

The Hydrostove looks like a regu- 
lar wood stove, but it operates quite 
differently. Rather than a solid cast- 
iron grate, the hydronic stove's 
firebox is a network of water-filled 
pipes. These pipes completely encircle 
the fire, with the burning wood being 
placed directly on the pipes. Photos 2 
and 3 demonstrate this. The inlet and 
outlet of this water jacket are acces- 
sible through two pipe fittings on the 
rear of the stove. (Since I knew that I 
wanted a hydronic stove when I built 
the Circuit Cellar, I had the pipes in- 
stalled behind the brick wall and 



34 February 1980 © BYTE Publications Inc 



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BYTE February 1980 35 



HYDRO/AIR HEATING SYSTEM 



HOT WATER ZONE 



ZONE 3 

CIRCUIT CELLAR 
BASE BOARD 



\\\\\\\\ 



-HOT AIR ZONES- 



BEDROOMS 



a 



ZONE 3 

WALL 

THERMOSTAT 

< T C3> 





Fl AND F2 
ARE INTERNAL 
AQUASTATS 



STANDARD OIL 
HOT WATER BOILER 
APPROX. 120,000 BTU/HR 



ZONE 2 
WALL 

THERMOSTAT 
(T C2 ) 




ZONE I 

WALL 

THERMOSTAT 

<T C |> 



VALVE A 




hx] 5h 



Figure 1: Diagram of the hydro/air, oil/wood 
heating system in use by the author. 



T IN 
IN 


T OUT 
OUT 







BURNER CONTROL ON/OFF 



HYDRONIC WOOD STOVE 

APPROX. 50,000 BTU/HR TO WATER 

AND 12,000 BTU/HR RADIATED 



WOOD FIRE 



through the ceiling. The oil burner is 
about 35 feet from the Hydrostove.) 
When a fire is started in the stove, the 
heat is extracted through the water 
rather than being radiated directly 
into the room. 

With dry, hard wood, the stove 
generates about 62,000 BTU per hour 
(with an additional 12,000 BTU per 
hour going up the chimney) and is 
quoted by the manufacturer to be 
about 85% efficient. I cannot say at 
this time exactly how much of this is 
transferred to the water as opposed to 
how much is radiated. I can only state 
my experience: with the stove burn- 
ing at full capacity for 6 hours, the 
brick wall 1 foot from the stove is on- 



ly warm to the touch, and wood can 
be piled next to the stove (about 2 
inches away) with no possibility of 
ignition. For this same 6-hour period, 
the Circuit Cellar temperature will 
never exceed 75° ¥ unless a higher 
temperature is set on the central 
heating system thermostat. You 
would definitely know that it is a hot 
stove, but anyone inspecting the rag- 
ing fire inside is usually quite sur- 
prised how little heat is felt in com- 
parison to a regular wood stove. 

A New England Experiment — 
First, the Basics 

The heating system shown in figure 
1 is commonly called a hydro /air 



system. It consists of an oil hot-water 
boiler and hot-air heat distribution. 
The oil burner heats water, which in 
turn circulates through a hot-water 
heat exchanger. A fan blows over the 
heat exchanger coils and circulates 
the hot air through the ducts to each 
room. Such a system combines the 
even-temperature, residual-heating 
benefits of a hot-water circulator with 
the pleasant, humidified, filtered 
warmth of a hot-air system. A third 
zone of baseboard heat was added 
when the Circuit Cellar was built. 

Perhaps the best way to start is to 
explain how an oil-fired hot-water 
heating system works. Neglect for a 
moment zones 1 and 2 and the 



Note: The heating system in this 
article is installed in my home and 
was built to my specifications. I do 
not intend this as a general con- 
struction article, but rather a 
documented discussion of the ele- 
ments of the system with emphasis 
on the controls involved. I must 
point out that while this article 
specifically describes a computer- 
controlled hydro heating system, 



general use of a Hydrostove does 
not require the sophisticated con- 
trol I have outlined. It is only the 
unique combination of machinery 
and an empirically determined 
operating algorithm that suggests 
ease of operation through com- 
puterization. In truth, the com- 
puter's primary value is in the ad- 
dition of a significant measure of 
safety rather than the convenience 



implied. Through its attachment as 
a supervisory controller, the com- 
puter can more accurately main- 
tain safe operating temperatures 
and dump excess heat in an over- 
temp condition. As of the time of 
this writing, two cords of wood 
have been burned in the stove 
testing this complete system and 
the result has been safe, satisfying, 
and reliable operation. 



36 February 1980 © BYTE Publications Inc 



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Hydrostove in figure 1. Think of it 
strictly as the oil burner connected to 
one circulator pump and the zone 3 
baseboard. This is essentially what 
many homes have. There may be 
multiple rooms, but only one circula- 
tion loop. 

Most people think that the thermo- 
stat on the wall turns the oil burner 
on. Actually, this thermostat only 
controls the on/off operation of the 
circulator pump; it generally has no 
direct connection to the burner itself. 
Operation of the boiler depends upon 
the temperature of the water flowing 
into the heating coil section and the 
temperature setting T A of the aquastat 
(water conduit thermostat). Water 
flows from the hot-water boiler to the 
baseboard and is drawn back through 
the circulator pump to the boiler 
again. If the temperature of this water 
is greater than the aquastat setting, 
the burner stays off. If however, the 
temperature is below T^, the burner 
turns on, adding heat until the water 
in the loop reaches T^ . Usually T A has 
a wide hysteresis; the high and low 
limit of variation is separated by 
about 20° F. For most boilers the low 
setting is 160° F, and the high is 180° 
F. The hysteresis reduces the frequen- 
cy of oil burner starts. 

To get heat in a room, you turn up 
the wall thermostat, which starts the 
pump. As the water moves through 
the baseboard, it loses heat to the 
room. The water is then reheated by 
the oil burner. 

Now, consider the addition of the 
Hydrostove as shown in figure 1. 
Any water circulating through zone 3 
will necessarily pass through the coils 
of the stove if valves A and B are 
opened and C is closed. This circula- 
tion in itself does nothing to the 
operation of the heating system. If, 
however, you build a fire in the 
Hydrostove as in photo 3, heat is 
added to the water returning from the 
baseboard and flowing into the 
boiler. If the fire is large enough, the 
temperature of the water flowing out 
of the Hydrostove is greater than T A , 
the oil burner never turns on, and the 
house will effectively be heated by the 
Hydrostove. 

There are a few other considera- 
tions. Unlike the oil burner which can 
be selectively turned on when heat is 
needed, once the wood stove is on, it 
runs for quite a while and the heat 



must be continuously removed; 
otherwise, the water in the pipes will 
turn to steam. Pressure-relief valves 
will keep the system from exploding, 
but who wants a steam bath in their 
living room? In a single-zone system, 
the circulator pump must remain on 
until the fire is out. In a gravity-feed 
system, the pump must stay on until 
the fire is lowered to the point where 
the water stays below the boiling 
point and can effectively be radiated 
by the heating loop. 

Consider the Hydrostove as a con- 
tinuous source of heat. If the 
Hydrostove is cranked up to produce 
40,000 BTU per hour, then 40,000 
BTU per hour must somehow be 
removed. The task of heat dumping is 
much easier on a multi-zone system. 
Take for example, three zones with 
capacities of 40,000 BTU, 30,000 
BTU, and 20,000 BTU, respectively. 
Whether or not a room thermostat is 
calling for heat, you must turn on 
either the pump for zone 1, or the 
pumps for both zones 2 and 3. Con- 
sider the case when zones 2 and 3 are 
used as heat dumps. If the zone 1 
thermostat were to trip suddenly, the 
control system would have to make a 
choice. It could add zone 1 to the pool 
and share 40,000 BTU among three 
zones or immediately drop zones 2 
and 3 off the line and send everything 
to zone 1 until it reaches its ther- 
mostat setting again. While the 
previous choice can easily be made, 
load sharing is an interesting con- 
sideration. It is much easier to switch 
zones on and off while performing 
load sharing than to try to directly 
control the heat output of the wood 
fire to any degree. 

An additional complication occurs 
when using heat exchangers. Heat 
exchangers cannot effectively transfer 
heat unless the blower is on. The fans 
in these units are thermostatically 
controlled. When the water flowing 
through the exchanger reaches a set 
temperature, the fan turns on, 
extracting heat. There is considerable 
delay and overshooting in the opera- 
tion of these units. While the average 
hourly heat transfer of a heat 
exchanger might be 40,000 BTU, it 
may be 10,000 BTU with the blower 
off and 50,000 BTU with it on. In a 
quick heat-dump situation, it is 
sometimes necessary to override the 
blower thermostat and force the 



P.O. Box 11174, Honolulu, Hawaii 96828 
Telephone (808) 734-5801 



38 February 1980 © BYTE Publications lnc 




i 1 

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Circle 21 on inquiry card. 



BYTE February 1980 39 




Photo 4: The computer I/O interface for the heating control system is attractively hous- 
ed. It includes a display of either the input or output temperature of the Hydrostove and 
a real-time status display of the circulators and blowers. 



blower on to maintain stable condi- 
tions throughout the rest of the 
system. 

Using a Hydrostove 

How much you benefit from the 
addition of a hydronic wood stove 
depends quite heavily on the rest of 
your heating system. Above all, it 
must be capable of taking the full heat 



output of the wood fire. This can be 
62,000 BTU per hour. Since my oil 
burner is rated at 120,000 BTU per 
hour, and I had added the third zone 
of baseboard to the Circuit Cellar, I 
concluded that the connection would 
be quite safe. 

My usual method of manual opera- 
tion is to use the stove only on very 
cold days and to build as large a fire 



Control 


Outputs 








Signal 


Type 






Function 


TC, 


Contact closure 
200 mA 






Circulator pump - zone 1 


TC, 


Contact closure 
200mA 






Circulator pump - zone 2 


TC 3 


Contact closure 
200 mA 






Circulator pump - zone 3 


F, 


Solid state relay 
5 A 220 VAC 






Heat exchanger blower 
zone 1 


F, 


Solid state relay 
5 A 220 VAC 






Heat exchanger blower 
zone 2 


XFER 


Contact closure 
5 A 115 VAC 






Oil burner power 


Inputs 










Status 


Level 


Function 




TC, 


TTL 








TC 2 


TTL 


pump 


off 




TC 3 


TTL 


1 pump 


on 




F, 


TTL 


blower 


off 




F, 


TTL 


1 blower on 




T,„ 


Analog 










range 40° to 240° 


F 


T„ 


Analog 


4° to 115° 


C 



Table 1: Computer I/O lines used with the heating control system. 



as possible. It is initially started with 
both dampers open, but once the fire 
is going strong the flue damper is 
closed to reduce the amount of heat 
going up the chimney. At the time the 
fire is started, the zone 1 circulator 
pump is turned on continuously with 
a switch, overriding the motor-start 
relay. This keeps some water flowing 
through the stove at all times. Zones 
2 and 3 are normally left in their "heat 
on demand" thermostat-controlled 
mode. If the Circuit Cellar cooled 
down and its circulator pump kicked 
in, it would be drawing heat from the 
stove along with zone 1. 

Our house is large, but given my 
method of use, no single heating zone 
can sustain the full output of the 
Hydrostove for long periods of time. 
Generally, the water temperature will 
be between 75° and 90° C. To main- 
tain a 20° to 22° C (68° to 72° F) 
temperature through the house on a 
very cold day, I have to keep the fire 
box continually filled. This means 
filling the stove with wood every 3 to 
4 hours. (Before you choke and com- 
pare it to 12 hours for a regular air- 
tight stove, remember that I am talk- 
ing about heating a whole house). 
After a few hours of use, even in this 
large house, the temperature in the 
rooms in zones 2 and 3 will reach the 
wall-thermostat set points, no longer 
continuously demanding heat from 
the stove. This leaves all the heat go- 
ing to zone 1. 

Soon, the temperature of the water 
coming out of the wood stove starts 
to climb above the safe high limit of 
88° C (measured 35 feet away at the 
furnace). When the indicator hits 
around 98° C, a loud noise can be 
heard in the pipes because the higher 
temperature water nearest the hot 
coals within the stove is turning to 
steam. Unless you want the safety 
valve to blow, filling the room with 
steam, you have to override the 
automatic settings of either or both of 
the thermostats of zones 2 and 3 to 
get rid of some of the excess heat. It 
may also be necessary to manually 
turn on the heat-exchanger blowers 
for zones 1 and 2 for the reasons I 
previously outlined. 

This occurrence is rare, and I 
generally have about 10 minutes to 
react to the situation and throw all 
the manual switches required. After 
using the system and determining that 
this is a potential problem, I installed 
a digital temperature indicator that 



40 February 1980 © BYTE Publications Inc 



■ 



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BYTE February 1980 41 



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allowed me to monitor the system as I 
worked at my desk in the Circuit 
Cellar. When I saw that the 
temperature was going above 88° C, I 
would throw the manual override on 
the zone 2 circulator pump. If the 
temperature did not drop, I would 
continue with the other heat dumping 
methods. It has never gotten to a 
point where these maneuvers prove 
insufficient or where the fire has to be 
put out. Experience has shown that 
zone 2's volume of 15,000 cubic feet 
provides a terrific sink for excess 
heat. Normal use in this mode barely 
raises its temperature more than 2° F 
above its nominal 66° F thermostat 
setting. (I do not want to leave you 
with the impression that there is one 
90° F room in the house.) 

I have not described anything thus 
far that specifically requires com- 
puterization other than for conven- 
ience. The real reason is a rather in- 
significant detail that is discovered 
only after actually using the stove. A 
Hydrostove definitely saves oil, as 
stated. When its output temperature 
is greater than the aquastat set point, 
the oil burner does not come on. The 
problem arises during startup and 
shutdown when the stove output 
temperature (T ou ,) is less than the set- 
ting of the aquastat (T^). The cir- 
culator pump has to remain on while 
there is a fire but, because the circula- 
tion loop is running and returning at 
less than T A , the oil burner keeps 
coming on. Catch 22!! 

If this were a matter of 10 minutes 
or so, it would not be so bad; but 
shutdown to the point where the cir- 
culator pump can be turned off can 
take several hours. The alternative is 
to cut the power to the oil burner 
when the wood stove is on and 
restore it when the fire is out. This is 
what I initially did, until I was stay- 
ing up all night to shut the stove off. 
The alternative was to wake up to a 
very cold house, turn the oil burner 
on, and have to wait a half-hour to 
take a hot shower. 

Aside from taking in a tenant who 
would watch the Hydrostove tem- 
perature in exchange for room and 
board, the only reasonable alter- 
native was a more intelligent control 
system. With the proper sensors, a 
device could monitor the heat output 
of the stove (T ou , — T,„), and when it 
dropped to a predetermined safe 
point, automatically restore power to 

Circle 23 on inquiry card. 



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'MACHINE LANGUAGE CALLABLE FORMS 



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Apple is a registered trademark of Apple Computers, Inc. 



DDL DATA DEFINITION LANGUAGE ANALYZER/ED 
ITOR. The user specifies data structures to be used in a 
Concise Data Definition Language (DDL). The Data Defini- 
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create and edit DDL Specifications and to initialize the data 
base for use based on these specifications. 

260 PAGE USERS MANUAL with extensive documentation 
of the Data Base Management System 

DMS DATA MANAGEMENT ROUTINES. These are the 
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8080 and 6502 VERSIONS 

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UPGRADE TO MDBS 



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8080 and 6502 VERSIONS 

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ADD S2.50 (S6.D0 IF FOREIGN! TO NON-CASH ORDERS 
FOR HANDLING AND SHIPPING. INDIANA RESIDENTS 
ADD 4%. 



Circle 24 on inquiry card. 



BYTE February 1980 



43 



2a C START J 



2b 



ACTIVATE HYDRO 
STOVE CONTROL SYSTEM 



DESIGNATE HEAT 
DUMP PRIORITIES FOR 
THE THREE ZONES. 
(IN MY CASE THEY ARE 
ZONE I , ZONE 2, ZONE 3) 



SET CONTROL TO AUTO 
MODE, TURN OFF OIL 
BURNER POWER AND TURN 
ON ZONE I CIRCULATOR 



95°C - 
90°C- 
88°C- 
75°C- 
60°C- 



NORMAL OPERATING 
TEMPERATURE 



HIGH ALARM (OVERTEMP) LIMIT 
LOW ALARM LIMIT 

HIGH PROCESS LIMIT 

LOW PROCESS LIMIT 
COOLDOWN 




YES 



YES 





YES 



TURN OFF 
ZONE I PUMP 
AND SET TO 
MANUAL MODE 



RESTORE POWER 
TO OIL BURNER 



TURN ZONE I 
BLOWER ON 



TURN ZONE 
BLOWER OFF 



YES 



( EX ' T ) 





TURN ZONE 2 
CIRCULATOR ON 



TURN ZONE 2 
CIRCULATOR OFF 




YES 




TURN ZONE 2 BLOWER 
AND ZONE 3 
CIRCULATOR ON 
AS REQUIRED 



TURN ZONE 2 BLOWER 
AND ZONE 3 
CIRCULATOR OFF 




YES 



TURN ON AUDIBLE 
ALARM AND 
INITIATE SHUTDOWN 
PROCEDURES 



TURN OFF ALARM 



Figure 2: (a) Logic flow for the automatic distribution of Hydrostove heat when output in a three-zone combination hydro and air 
heating system, (b) Points of importance in the operating temperature range of the system. The actual set points for process and alarm 
limits depend upon placement of temperature sensors and may vary a few degrees. 

In BYTE, algorithmic flow is assumed to proceed down and to the right unless an arrowhead is present to indicate otherwise. 



44 February 1180 © BYTE Publications Inc 



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Circle 25 on inquiry card. 









Equivalent 








gallons 


Type of wood 


Pounds per 


BTU per cord 


(gallons per cord) 


Hardwoods 


cubic foot 




fuel oil 


1. White Ash 


37.5 


23,037,000 


165 


2. Cherry 


31.0 


19,043,920 


136 


3. Hickory 


45.0 


27,644,400 


198 


4. Maple (red) 


33.5 


20,579,720 


147 


5. Oak (chestnut) 


41.0 


25,187,120 


180 


6. Walnut 


34.5 


21,194,040 


151 


7. Willow 


24.0 


14,743,680 


105 


Softwoods 








8. Douglas Fir 


30.0 


18,429,600 


132 


9. Ponderosa Pine 


25.0 


15,358,000 


110 


10. White Spruce 


25.0 


15,358,000 


110 



Table 2: Comparison of wood heat values for various species of wood available in 
North America and their equivalent in gallons of fuel oil per cord of wood. (These 
estimates are generally accepted by industry.) 



the burner and shut off the circulator- 
pump override. 

Computer-Controlled 
Heating System 

My heating system is not tech- 
nically a computer-controlled wood 
stove. It is rather a system designed 
specifically to efficiently distribute 
the heat from a wood stove, to safely 
dump excess heat in an effective man- 
ner, and most importantly, to restore 
the entire system to its standard con- 
figuration when the fire is out. I am 
merely outlining one application of 
the many that are conceivable when 
the heating system has been con- 
nected to a computer. Complete 
energy management is a possibility; 
or, at the very least, total energy out- 



put can be closely monitored and 
recorded. I am working on these 
areas, but for now, the topic is con- 
trol. 

Virtually any personal computer 
can suffice as the controller. The logic 
is straightforward and relatively un- 
complicated. It is outlined in the 
flowchart shown in figure 2. Proper 
control of the three zones and the 
Hydrostove requires a special inter- 
face to connect the computer to the 
various blowers and pumps. Table 1 
is a list of the signals in question. 

The control outputs from the com- 
puter are, in essence, all contact 
closures, whether it be through 
mechanical or solid-state relays. The 
use of relays provides electrical iso- 
lation between the computer and the 



heating system. It further prevents 
potentially dangerous loops between 
115- and 220-VAC powered compo- 
nents. 

The three zone thermostats are 
low-voltage AC circuits that can be 
directly controlled through a reed 
relay, as shown in figure 3. The relay 
contacts are connected in parallel 
with the thermostat. With the 
thermostat contacts open, a logic 1 
control signal closes the relay and 
provides an alternate current path to 
pull in the pump-start relay. By 
monitoring the voltage across the 
relay contacts, it is possible to direct- 
ly monitor the activity of the cir- 
culator pump and determine its 
operational status at any time. If the 
contacts are open, current flows 
through the optoisolator light- 
emitting diode (LED), producing a 
logic status at the output. When 
closed, no current flows and the logic 
value is 1. My application required 
only the ability to turn on a pump 
which may not already be running. 
However, to accommodate complete 
functional control of the pumps, the 
thermostat can be disconnected as 
shown. 

The interface to the heat exchanger 
blowers, shown in figure 4, is similar. 
This time however a solid-state 7 A 
220 VAC relay is used. The power to 
the blower is 5 A 220 V rather than 
low voltage AC as before. A 7 A 
solid-state relay was chosen because 
of its size and low cost. 



FROM 
PARALLEL 
OUTPUT 
PORT 



COMPUTER INTERFACE 



ICI 
7406 



ctlO 



STATUS <CD- 



NORMALLY 
OPEN 



+ 24V 



^>c^ 



A IN9I4 



+ 5V 



; 2.2K 



TTL LEVEL 
SIGNAL TO 
PARALLEL 
INPUT PORT 



LITR0NIX 

IL-I 

OPTOISOLATOR 



> 



COMPUTER 
GROUND /77 



IN400214) 



100/iF -r 
50V 



-w- 



NORMALLY 
OPEN 



-o 



fl 



ROOM 

THERMOSTAT 

55°-80°F 



-o 



PUMP MOTOR 
START RELAY 



15- 30 VAC ' 



<3 






I20VAC 



-<3 



'DISCONNECT THERMOSTAT IF COMPUTER IS TO 
HAVE SOLE CONTROL OF CIRCULATOR PUMP. 



CTL 

I 



DON T CARE 



ERMOSTAT 


PUMP 


STATUS 


OPEN 


OFF 





OPEN 


ON 


1 


CLOSED 


ON 


1 



Figure 3: Isolated interface for computer control of a typical oil-fired, hot-water, 1/4-horsepower circulator pump. The 7406 open- 
collector inverter (ICI) requries a 5 V supply to pin 14 and a ground connection to pin 7. 



46 February 1980 © BYTE Publications lnc 



m 






WllkliKK 



the answer. 



m 



Corvus— the company that brought Winchester technology to 
the microcomputer— is now delivering the solution to backup 
for less than $1500. 

It's called the Corvus MIRROR®, a backup employing low- 
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Corvus is the company that gives you a complete systems 
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408/246-0461 



«** 




t Apple Is a registered trademark of Apple Computers, Inc. 
ITRS-B0 Is a registered trademark of Radio Shack, a Tandy Co. 



Circle 26 on Inquiry card. 



' 



FROM 

PARALLEL . — . 

OUTPUT CTL V-S>- 

PORT 



STATUS <ZJ- 
TO 

PARALLEL 
INPUT PORT 



COMPUTER INTERFACE 
+ 5V 



HEAT EXCHANGER BLOWER 



ICI 
7404 

0* 



ICI 

7404 



7A 220V 

SOLID STATE RELAY 



SIGMA 
226REI-5AI 



OUT 



fj 



+ 5V 



LITRONIX 

IL-I 

OPTOISOLATOR 



HEAT EXCHANGER 
THERMOSTAT 
120°- 200°F 



220 VAC 




o 



> 



4 

m 



. IN5252 
24 V 
ZENER 



IOOjiF 
50V 



A IN4004(4) 

-W-l 



<H 



I2K 
I0W 



CTL 


THERMOSTAT 


BLOWER 


STATUS 





OPEN 


OFF 





1 


OPEN 


ON 


1 


DON'T CARE 


CLOSED 


ON 


1 



Figure 4: Isolated interface for computer control of a heat-exchanger blower fan. The 7404 hex inverter requires a 5 V power supply to 
pin 14 and a ground connection to pin 7. 



Monitoring the activity of the 
blowers is accomplished simply by 
checking the voltage across the 
motor. The 220 V present when the 
motor is on is reduced and rectified to 
run an optoisolator as before. With 



voltage present, the status output is 
high (logic 1). 

Finally, the computer must be able 
to monitor the output temperature of 
the Hydrostove. This signal is an 
analog voltage that is proportional to 




Photo 5: An internal view of the I/O controller containing relays, optoisolators, and 
analog interface components. 



temperature. Various sensors such as 
thermistors or thermocouples could 
be used, but a more practical device is 
a temperature sensor device such as 
the LM334 from National Semicon- 
ductor. When configured as in figure 
5, the output of ICI (monitored at 
V,„) is 10 mV per degree Celsius. It 
may have a nominal offset of 
something like 2.5 V, but if the 
temperature rises 10° C the output 
will go up 100 mV. ICs 2 and 3 pro- 
vide gain and offset adjustment and 
are configured to prohibit accidental 
negative excursion of the output if the 
temperature sensor goes open circuit. 
The result is a circuit that converts a 
change in temperature to a change in 
voltage. By adjusting the gain and 
offset, 0° C can be an output of V 
and 100° C can be 1 or 10 V. A 
Fahrenheit scale can be just as easily 
calibrated by setting a different gain 
and offset. 

To read this signal, the computer 
must have an analog-to-digital con- 
verter interface. This can be either a 
true successive-approximation 
analog-to-digital converter as in 
figure 6, or the discrete set-point level 
detector of figure 7. The choice 



48 February 1980 C BYTE Publications Inc 



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1333 SOUTH CHILLICOTHE ROAD 
AURORA, OH 44202 • [21 6] 562-31 01 

Circle 27 on Inquiry card. 



+ 10 TO 15 V 




V ~ ADJUST 



V !N = lOmV/K 



VTEMP 
-C> 0-IOV 

0°-IOO°C 



(REDUCE RANGE TO LESS 
THAN 5V IF USING THE 
CIRCUIT IN FIGURE 6 ) 



Figure 5: Solid-state temperature sensor. The range of the output voltage (V TEMP ) is reduced to less than 5 V if the circuit in figure 6 is 
used. 



depends upon whether you need to 
know the exact temperature or just 
significant set points. 

If data acquisition is the dominant 
consideration, then consider the cir- 
cuit of figure 6. IC8 is an 8-channel, 
8-bit analog-to-digital converter that 
is bus-compatible with most micro- 
processors. Figure 8 outlines its inter- 
nal structure. As configured, it is 
attached to function as ports F8 
through FF, with port F8 correspond- 
ing to input channel 0, and port FF 
corresponding to channel 7. The volt- 




Photo 6: To effectively use this control 
device, it is important to have accurate 
temperature measurements. The LM334 
temperature sensor is easily attached to 
the Hydrostove return pipe by wrapping 
Teflon plumbing tape around it. 



age on channel is read by initiating 
an output to port F8. This causes the 
address of 000 to be stored and the 
conversion process started. After 
about 100 microseconds, the time 
necessary for conversion, the channel 
analog value can be obtained by 
reading an input from port F8. A 
similar procedure is used to set and 
read the other channels. 

If you are interested strictly in con- 
trol, then the circuit of figure 7 is 
much simpler to use. If a to 10 V in- 
put represents a range of to 100° C 
and there are eight comparators, each 
could be set to trigger 12.5° C higher 
than the preceding one. A better ap- 
proach is to arrange the majority of 
set points to cover the control and 
alarm range rather than to cover 
insignificant temperature ranges. For 
example, bit b could be set to trigger 
at 60° C. It is not necessary to care 
much about temperatures below that 
point. The range of prime interest is 



from about 75° C to 95° C. 
Dedicating 5 set points within this 
range, another perhaps between 60° 
C and 75° C and a final overtemp in- 
dicator at 98° C should prove more 
than adequate. 

My system uses a combination of 
both interfaces, using set points for 
control inputs and a true analog-to- 
digital converter to determine actual 
heat output from the stove. 

A further enhancement is a visual 
display indicating the real-time status 
of the system components and a 
readout of the actual temperature. 
The prototype controller is shown in 
photos 4 and 5. It serves as the inter- 
face between the heating system and 
the computer, and contains most of 
the electronics described in this article 
as well as other enhancements not 
discussed at this time. While all the 
control decisions are actually made 
by the computer, the display gives me 

Text continued on page 56 



Number 


Type 


+5V GND 


-12 V 


+ 15V 


IC1 


LM334 


see figure 5 






IC2 


LM301A 




4 


7 


IC3 


LM301A 




4 


7 


IC4 


LM339 


12 




3 


IC5 


LM339 


12 




3 


IC6 


REF-01 


see figure 7 






IC7 


LM301 


4 




7 


IC8 


ADC0808 


see figure 6 






IC9 


74LS30 


14 7 






IC10 


74LS02 


14 7 






IC11 


7400 


14 7 







Table 3: Power and ground connections 
for the integrated circuits that are used in 
the circuits of figures 5, 6, and 7. 



SO February 1980 © BYTE Publications lnc 




Here's to your health! Six Vitaf acts 
programs for you and your family 



Being healthy and happy is so very important. And now you 
can use your Applet PET/CBM'" or TRS-80'" computer to 
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Introducing six new Personal Software'" Vitafacts Series 
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About Sex, Drinking & Drugs, Birth Control, and Your Blood 
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Using a Vitafacts program is like getting advice from your 
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Each program includes a manual with diagrams and glossary, 
a computer cassette, and an audio 
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Growing Up helps families cope 
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Heart Attacks describes what one 
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TM-Vitafacts is a trademark of Medifacts Ltd.; 
Apple is a trademark of Apple Computer, Inc.; PET 
is a trademark of Commodore Business Machines, 
lnc.;TRS-80 is a trademark of the Radio Shack Div. 
ofTandyCorp. 

Circle 28 on inquiry card. 



-most important— 




when someone is experiencing one, and- 
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Talking About Sex, presented by two of Canada's fore- 
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Drinking & Drugs. No lecturing or talking down. Just 
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A7 £>- 

A6C^ 
A5C^ 
AlC^ 
A3 O" 



A2 O- 
Al Q>- 

A0[> 




Rl 
IK 

10 TURN 
POTENTIOMETER 



> 




^°y^ 



OPTIONAL 
INTERRUPT 



D- 




V REF = 5.000V 



-u 



25V 
TANTALUM 



OUT 
ENABLE 



ADDRESS 

LATCH 

ENABLE 



ICB 

ADC0808 



'CC 
GND 



-o»« 

-OD2 

-D>m 
-D»' 

-OD5 
-(Z>D6 
-D>D7 



COMPUTER I/O 
DATA BUS 



^]|N0 
^CHlNl 
-<Ol«2 
-<ZllN3 
-OH™ 
^dlN5 
-<Z|lN6 

-On" 



8 ANALOG INPUTS 



IC11 
j. 1 » 7100 

V , I * — • d llo 2 



680pp 



CLOCK FREQUENCY 
NOMINAL 500kHz 



Figure 6: An 8-channel, 8-bit analog-to-digital (A/D) converter using a National Semiconductor ADC0808 data acquisition device. 



FINALLY, Apple II software for the discerning computerist, 
and the not-so-discerning beginner 



AppleAids 



Little Tricks ™ 

A series of carefully explained subroutines containing a potpourri of 
useful programming techniques in Integer Basic and Applesoft, such as 
specific key stroke identification, timing loops, disappearing question 
marks on input, no question marks on input, and many more. 
Cassette (24K) 14.95 Disk(32K) 19.95 

Scroll Control" 

Have you ever wondered why you cannot list an Integer Basic or 
Applesoft program one screen-page at a time? So have we. and we 
did something about it! Our machine language Scroll Control, hidden 
in RAM so as not to "bump" into your program, can be engaged or dis- 
engaged at a flick of the keyboard. Why be frustrated when instead you 
can control the scroll? Cassette 9.95 Disk 14.95 

Compulaw™ Series 

Alitax Estimator™ 

This Applesoft program, prepared under the supervision of an attorney, 
estimates disposable income after alimony and child support payments 
and federal taxes. For use by laymen and attorneys. 1980 tables. 
Cassette (24K) 9.95 Disk (32K) 14.95 

Pensionner™ 

A companion to Alitax Estimator in Applesoft designed to calculate the 
present value of a pension in states in which a pension is subject to 
division in marital dissolution cases. 
Cassette (24K) 9.95 Disk (32K) 14.95 



N.J. res. add 5% sales tax 

Apple II and Applesoft are registered 

trademarks of Apple Computer, Inc. 
Add $1.50 /item, shipping and handling 
'professional, but not a substitute for 

legal advice 



Form-It-Out™ 

A series of routines in Integer Basic and Applesoft containing detailed 
explanation and examples of programming techniques necessary to 
professionalize your screen output. Included are right and center justi- 
fication, windowing, tabbing, cursor positioning among others. 
Cassette (24K) 14.95 Disk (32K) 19.95 

Track & Sector List™ 

This is the ultimate disk utility. Instead of a catalog, have you ever seen 
those dreaded words "I/O ERROR"? Is all lost? NO! Now your disk may 
be saved. Also you can eliminate bad sectors, remove control characters 
imbedded in file names, and more. This machine language program is 
supplemented by extensive tutorial documentation worth its weight in 
gold. Disk only (32K) 29.95 

Hex ecimal Learning Tree™ 

My ABC's™ 

An early learning Integer Basic program using over one hundred and fifty 
high resolution graphic letters and pictures in a drill-and-practice tormat 
designed to develop identification of capital and small letters, and 
association of letters with pictures. Scoring capability allows monitoring. 
Child tested and teacher recognized. Cassette (48K) 14.95 Disk 19.95 

Now I Can Rhyme™ 

A companion to My ABC's in Integer Basic. The child selects those high 
resolution pictures which rhyme. Score-keeping capability allows 
monitoring. Incorporates progressive levels of difficulty. 
Cassette (48K) 14.95 Disk (48K) 19.95 




P.O. Box 774M 
Morristown, NJ 07960 
(201)539-3770 



INCORPORATED 



52 February 1980 © BYTE Publications Inc 



Circle 29 on inquiry card. 




BYTE February 1980 53 



VOLTAGE REFERENCE 



SETPOINT ADJUST POTS 




+ VREF 



2907 



'i o 



io.ooov 



m 



VinO 



NOTE: COMPARATOR OUTPUT IS LOGIC WHEN 
V| N IS LESS THAN SETPOINT. 

OUTPUT IS LOGIC I WHEN V| N IS EQUAL 
TO OR GREATER THAN SETPOINT. 




OB 



'I 



OBI 



OB2 



OB3 



8 BIT 
. PARALLEL 
/ INPUT 

PORT 



0»B4 



C>B5 



OB6 



OB7 



Figure 7: A discrete set-point-level detector. This method is cheaper than the method shown in figure 6 and can be used only -when it is 
necessary to detect a small number of temperature ranges. The eight comparators on the right-hand side of the figure are wired to 
have their outputs go from logical to logical 1 when a certain temperature (determined by the position of the 10 K potentiometer) is 
exceeded. The status of the eisht bits can be used to determine what range of temperature the interface is currently in. The voltage 
reference integrated circuit REF-01 (IC1) may be obtained from Precision Monolithics, 1500 Space Park Dr, Santa Clara CA 95050. 



54 February 1980 © BYTE Publications Inc 




IS READY . . . 



WITH SYSTEMS AND SOFTWARE! 

... Feel Free to Mil and Match 



SVSTEIV1 1 




$1750.00 



T win Mini IU/32K 

SYSTEM? 



1 - $139.00 

Leedex monitor 



"l " V 



$110.00 

Keyboard 




Base 2 



$499.00 



IYIULTIUSER CAPABLE 




$1650.00 




$775.00 





3 2K 8-100 mainfra me T/v 912 Terminal 

SYSTEM? 



Tl 810' 



$1350.00 

1 Megabyte 
Double Density storage 



IYIULTIUSER CAPABLE 




$1950.00 




$985.00 





$1850.00 



64 K s-too Mainfra me T/u I 

systeRu 



$3450.00 

Diablo 1620 



2 megabyte 
Quad Density storage 



MULTIUSER 



t (Dealers Only) 





tDesk Enclosure 



Software: 

CPM 1.4 $115.00 

CPM 2.0 $150.00 

MPM MULTIUSER . $350.00 



32 megabyte dish 




atit model 300 



CBASIC . . 
MBASIC . . 
FORTRAN 
COBAL. . . 
PASCAL . . 



$115.00 WORDSTAR $495.00 

$300.00 ACCTS. PAYABLE. . . . $699.00 

$395.00 ACCTS. RECEIVABLE . $699.00 

$625.00 GENERAL LEDGER. . . $899.00 

$265.00 SUPERSORT $225.00 



DATABASE . . . 
INVENTORY . . 

QSORT 

NAD 

LETTERRIGHT 



SI 50.00 
$440.00 
$ 95.00 
S 79.00 
S 180.00 



West: 

DELTA PRODUCTS 

1653 E. 28th Street 
Long Beach, Calif. 90806 
Tel: (213)595-7505 

Circle 31 on Inquiry card. 




East: 

DELTA PRODUCTS 

1254 South Cedar Road 
New Lenox, Illinois 60451 
Tel: (815)485-9072 



Telex: 182-126 DELTMAR SGHL 



START 



CLOCK 



ANALOG { 
INPUTS 



C> END OF CONVERSION 



6 CHANNELS 
MULTIPLEXING 
ANALOG 
SWITCHES 







ADDRESS 
DECODER 




V cc GND REF(+) 



REF(-) 



TRISTATE CONTROL 



Figure 8: National Semiconductor's ADC0808/0809 CMOS data acquisition system. The 8-bit converter uses successive approxima- 
tions. The device interface is to most 8-bit microprocessors. 



Text continued from page 50: 

the added satisfaction that everything 

is working correctly. 

Back to Roger's Visit 

Roger studied the stove very 
carefully. He was surprised at the 
simplicity of the idea of supplemental 
wood heat, but somewhat aghast at 
the overall complexity of the entire 
system. The concept of computer 
control did not concern him in the 
least but I sensed that my apparent 
independence from OPEC fostered a 
little competitive jealousy. 

"What about wood? You still will 
have to get wood for the stove," 
Roger commented, pointing out a 
possible serious limitation. 

"I'm surprised you didn't notice 
when you drove in. There are eight 
cords of wood piled outside. I don't 
expect to use them all this winter. 
Wood, unlike oil, is one of those 
things you can easily stockpile if you 
have enough storage space." 

"Oh yeah, I did notice a few piles 
beside the driveway." 

Roger was perplexed. He had ob- 
viously begun to believe the petro- 
leum company propaganda. The 
thought of missing an oil delivery 
meant total destruction of civilization 



as far as he was concerned. But he 
just could not believe that the addi- 
tion of a wood stove meant indepen- 
dence. Suddenly he smiled as he 
thought of a sobering reality that I 
might have overlooked. 

"You have to keep the circulator 
pumps running when the stove is 
going, right? And if the fire is real hot 
you may in fact need the blowers on 
as well?" 

"Sure, why?" 

Roger had found the Achilles' heel 
of my heating system. The Hydro- 
stove as I had it configured needed 
power to run all the pumps and 
blowers. The actual heat might come 
from a wood fire, but distribution of 
the heat throughout the house 
depended upon the local electric util- 
ity. Roger quickly commented, 
"What happens if the power goes 
out?" 

"Well, I suppose I should be con- 
cerned, but I'll have four or five 
minutes to react." 

Roger laughed. "React to what? 
Living in a steam bath?" 

"Perhaps I should show you. 
Follow me." I led Roger out of the 
cellar into the garage. In one corner 
was a large mechanical contraption, 
part of which was a two-cylinder 



engine. Pipes and wires came to it 
from different directions, all converg- 
ing at a central control box adjacent 
to the motor. Without explaining the 
intricate details involved with this 
permanent installation (the heating 
system was enough for Roger this 
time) I said, "If the utility power goes 
out, I throw the emergency transfer 
switch and start my 5-kilowatt gener- 
ator. It's large enough to run the 
whole house and then some." 

Hesitating, then striking out with 
one last effort, 'You still need 
gasoline and that doesn't look like a 
very big tank." 

"Sorry Roger, I thought of that 
too. This particular unit runs on both 
gasoline and propane. There's a 
100-gallon propane tank outside the 
garage just for the generator" 

"I give up!" 

It is just as well that he did. Event- 
ually he would notice the trench 
going across the driveway from the 
house to the new garage. When he is 
installing the wiring for it I hope he 
doesn't ask why I am running insu- 
lated copper pipes underground 
across to the garage. 
NEXT MONTH: Investigate the new 
Intel 8088 processor and build your 
own five-chip computer. ■ 



56 February 1980 © BYTE Publications lnc 



26 MEGABYTES 




Suddenly, S-100 microcomputer systems can easily handle 100 million 
bytes, because Morrow Designs™ now offers the first 26 megabyte hard disk 
memory for S-100 systems-the DISCUS M26™ Hard Disk System. 

It has 26 megabytes of useable memory (29 megabytes 
unformatted). And it's expandable to 104 megabytes. 

The DISCUS M26™ system is delivered complete- 
a 26 megabyte hard disk drive, controller, cables and operating systemVfor 
just $4995. Up to three additional drives can be added, $4495 apiece. I 

The DISCUS M26™ system features the Shugart SA4jp08 
Winchester-type sealed media hard disk drive, in a handsome metal cabinet 
with fan and power supply. 

The single-board S-100 controller incorporates intelli- 
gence to supervise all data transfers, communicating with the CPU via Y 
three I/O ports (command, status, and data). The controller has the ability to 
generate interrupts at the completion of each command to increase system 
throughput. There is a 512 byte sector buffer on-board. And each sector can pe 
individually write-protected for data base security. 

The operating system furnished with DISCUS M26™ 
systems is the widely accepted CP/M* 2.0. 

See the biggest, most cost-efficient memory ever intro- 
duced for S-100 systems, now at your local computer shop. If unavailable 
locally, write Morrow Designs,™ 5221 Central Avenue, Richmond, CA 94804L , 
Or call (415) 524-2101, weekdays 10-5 Pacific Time. 

*CP/M is a trademark of Digital Research. 



Q /MORROW DESIGNS™ 

Thinker Toys 



Circle 32 on inquiry card. 



' 



Solving Problems Involving 
Variable Terrain 

Part 1: A General Algorithm 



Scott T Jones 

271 NW 38th St 

Boca Raton FL 33431 



A General Definition of Terrain Problems 

In business, in industry, and especially in conflict 
simulation, problems are often confronted that involve 
terrain, the surface of the planet Earth. These problems 
can usually be expressed in terms of movement on a map. 
This article defines terrain as any feature on the map that 
affects movement. The term movement cost will be defin- 
ed as the quantitative effect of the terrain on movement. 

An example of a hiker traveling cross-country from 
one town to another town will be used. The hiker may 
travel one mile across level ground in 15 minutes, while 
requiring 30 minutes to travel one mile when the ground 
is sloping gradually upward. It can be said that the move- 
ment cost for the terrain called level ground is one, while 
the movement cost of the terrain called upward-sloping 
ground is two. Here the movement cost is in terms of 
time. 

For another example, consider a construction company 
building a road. The cost to build one mile of roadway 
over solid ground might be $100,000, while the cost to 
build one mile of road over marshy ground might be 
$500,000. Thus, you can say that the movement cost is 
one for solid terrain and five for marshy terrain. In this 
case, the movement cost is expressed in terms of money. 

In both examples, there is an existing problem of mov- 
ing from one point to another across a terrain map while 
incurring the minimum movement cost. Now examine 
another variation of this problem. 

58 February 1980 © BYTE Publications Inc 



Consider a cable television company that is investi- 
gating the extension of underground coaxial cables out to 
a new area. It is known that these new cables will provide 
a fixed return on investment due to the increased number 
of customers. Therefore, only a fixed amount of money 
can be spent to place these cables. Using a map of the ter- 
rain and the known costs of placement over the various 
types of terrain to be encountered, the company can 
decide whether the extension is feasible. 

The purpose of this article is to describe a general solu- 
tion to these and other related problems. 

Representing Generalized Terrain Problems 

The first step in solving a terrain problem is to 
superimpose a grid on the map that is to be used. This 
will allow you to refer to each location on the map via its 
coordinates and identify a particular type of terrain with 
each location. 

For simplicity, a standard rectangular grid and coor- 
dinate system will be utilized. The map is now a matrix of 
squares that can be referred to by their row and column 
in the matrix. The size of the squares should be chosen so 
that each square effectively has only one type of terrain 
in it. 

The second step is to determine the movement cost for 
each type of terrain. This requires that a study be made to 
determine the type of cost involved in the problem. This 
cost must then be scaled so the movement-cost figure for 

Text continued on page 62 



6809 PROCESSING POWER/ 

The Percom SBC/9. Only $199.95. 




Fully compatible w th the SS-SOjbuT™ 
requiring no modification of tbe'mother 
board, memory ojr l/0"^t6ts— ■ --.thfl 
SBC/9™ is also a coprfplete, single- 
board control corrjpuler with its own 
ROM operating! "systefTH -BA.M. 
peripheral ports and a full-range baud' 
clock generator. 



Make the SBC/9 the heart of your computer and put to work 
the most outstanding microprocessor available, the 6809. 



the Mighty 6809 

Featuring more addressing modes 
than any other eight-bit processor, 
position-independent coding, special 
16-bit instructions, efficient argu- 
ment-passing calls, autoincrement/ 
autodecrement and more, it's no won- 
der the 6809 has been called the "pro- 
grammers dream machine." 

Moreover, with the 6809 you get a 
microprocessor whose programs typ- 
ically use only one-half to two-thirds as 
much RAM space as required for 6800 
systems, and run faster besides; 

And to complement the extraordi- 
nary 6809, the Percom design 1 team 
has developed PSYMON™, an extraor- 
dinary 6809 operating system for the 
SBC/9" 
PSYM0N~— Percom SYstem MONitor 

Although PSYMON "includes a full 
complement of operating system 
commands and 15 externally callable 

"trademark of Percom Data Company, Inc. 



utilities, what really sets PSYMON" 
apart is its easy hardware adaptability 
and command extensibility. 

For hardware interfacing, you 
merely use simple, specific device 
driver routines that reference a table of 
parameters called a Device Control 
Block (DCB). Using this technique, in- 
terfacing routines are independent of 
the operating system. 

The basic PSYMON" command 
repertoire may be readily enhanced or 
modified. When PSYMON" first re- 
ceives system control, it initializes its 
RAM area, configures its console and 
then 'looks ahead' for an optional sec- 
ond ROM which you install in a socket 
provided on the SBC/9* card. This 
ROM contains your own routines that 
may alter PSYMON" pointers and 
either subtly or radically modify the 
PSYMON" command set. If a second 
ROM is not installed, control returns 
immediately to PSYMON" 



Provision for multi-address, 8-bit bidirec- 
tional parallel I/O data lines for interfac- 
ing to devices such as an encoded 
keyboard. 

A serial interface Reader Control output 
for a cassette, tape punch/reader or simi- 
lar device. 

An intelligent data bus: multi-level data 
bus decoding that allows multiprocess- 
ing and bus multiplexing of other bus 
masters. 

Extended address line capability — ac- 
commodating up to 16 megabytes of 
memory — that does not disable the on- 
board baud rate clock or require addi- 
tional hardware in I/O slots. 
On-board devices which are fully de- 
coded so that off-card devices may use 
adjoining memory space. 
Fully buffered address, control and data 
: lines. ' 



The SBC/9", complete with PSYMON"in 
ROM, 1K of RAM and a comprehensive 
users manual" costs lust $1 99.95. . 



PEFCOM 



PERCOM DATA COMPANY, INC. 

211 N. KIRBY GARLAND. TEXAS 75042 

(214)272-3421 

Percom peripherals for personal computing' 



To place an order or request additional literature 
call toll-free 1-800-527-1592. For technical infor- 
mation call (214] 272-3421 . Orders may be paid by 
check, money order, COD or charged to a VISA or 
Master Charge account. Texas residents must add 

5% sales tax. Circle 25 on inquiry card. 

PRICES AND SPECIF ICATIONS SUBJECT TO CHANGE WITHOUT NOTICE. 



Circle 33 on inquiry card. 



BYTE February 1980 59 



Welcome to Percom's Wide World 



Each LFD mini-disk storage system 
includes: 

• drives with integral power 
supplies in an enamel-finished 
enclosure 

• a controller/interface with ROM 
operating system plus extra ROM 
capacity 

• an interconnecting cable 

• a comprehensive 80-page users 
manual 

Circle 34 on inquiry card. 

Low-Cost Mini-Disk Storage in the Size You Want. 




Percom LFD mini-disk drive 
systems are supplied complete 
and ready to plug in the moment 
they arrive. You don't even have 
to buy extra memory. Moreover, 
software support ranges from 
assembly language program 
development aids to high-speed 
disk operating systems and 
business application programs. 

Mini-disk storage system prices: 



The LFD-400® and -400EX® systems 
and the LFD-SOO** and -800EX® systems 
are available in 1-, 2- and 3-drive 
configurations. The -400, -400EX drives 
store 102K bytes of formatted data on 
40-track disks, and data may be stored on 
either surface of a disk. The -800, -800EX 
drives store 200K bytes of formatted data 
on 77-track disks. 

The LFD-1000® systems (not pictured) 
have dual-drive units which store BOOK 
bytes on-line. The LFD-IOOO"- controller 
accommodates two drive systems so that 
a user may have as much as 1.6M bytes 
on-line. 





1 -DRIVE 


2-DRIVE 


3-DRIVE 


MODEL 


SYSTEM 


SYSTEM 


SYSTEM 


For the SS-50 Bus: 








LFD-400® 


$ 599.95 


$ 999.95 


$1399.95 


LFD-800® 


895.95 


1549.95 


2195.95 


For the EXORciser* Bus: 








LFD-400EX® 


$ 649.95 


$1049.95 


$1449.95 


LFD-800EX® 


945.95 


1599.95 


2245.95 


LFD-1000® 


(dual) $2495.00 


(quad) $4950.00 


— 




HlUjtll 

•llll ff If 




EXORciser Bus LFD-400EXP SOOEX^ Systems 




Circle 35 on inquiry card. 

Upgrade to 6809 Computing Power. Only $69.95 



Although designed with the SWTP 6800 owner in 
mind, this upgrade adapter may also be used with 
most other 6800 and 6802 MPUs. The adapter is 
supplied assembled and tested, and includes the 
6809 IC, a crystal, other essential components and 
user instructions. Restore your original system by 
merely unplugging the adapter and a wire-jumpered 



DIP header, and re-inserting the original 
components. Also available for your upgraded 
system is PSYM0M» (Percom SYstem MONitor), 
the operating system for the Percom 6809 
single-board computer. PSYM0N® on 2716 ROM 
costs only $69.95. On diskette (source and object 
files), only $29.95. 



Data Terminal & Two-Cassette 
Interface— the CIS-30+ 



, A , E TERMINA 






300 " Nl 




ON 


,200 l° CAl 


• 


I*' 
AUIO 


pEflSOM 




CIS-30+_ 


Circle 36 on 


inquiry card 



• Interface to data terminal and two casselte recorders 
with a unit only 1/10 the size of SWTP's AC-30. 

• Select 30, 60 or 120 bytes per second cassette 
interfacing: 300, 600 or 1200 baud data terminal 
interfacing. 

• Optional mod kits make CIS-30+ work with any 
microcomputer. (For M1TS 680b, ask lor Tech Memo 
TM-CIS-30+-09.) 

• KC Standard/Bi-Phase-M (double frequency) cassette 
data encoding. Dependable self-clocking operation. 

• Ordinary functions may be accomplished with 6800 
Mikbug* monitor 

Prices: Kit, $79.95; Assembled, $99.95. Prices include 
a comprehensive instruction manual. Also available: Test 
Cassette, Remote Control Kit (for program control of 
recorders), IC Socket Kit, MITS 680b mod documentation 
and Universal Adapter Kit (converts CIS-30+ for use with 
any computer). 



of 6800 Microcomputing. 



6800/6809 SOFTWARE 
System Software 

6800 Symbolic Assembler — Specify assembly options 
at lime of assembly with this symbolic assembler. Source 

listing on diskette $29.95 

Super BAS IC — a 1 2K extended random access disk BASIC 
tor the 6800 and 6809. Supports 44 commands and 31 func- 
tions. Interprets programs written in both SWTP 8K BASIC 
(versions 2.0, 2.2 & 2.3) and Super BASIC. Features: 9-digit 
BCD arithmetic, Print Using and Linput commands, and much 

more. Price $49.95 

TOUCHUP'* — Modifies TSC's Text Editor and Text Pro- 
cessor for Percom mini-disk drive operation. Supplied on 

diskelte complete with source listing $17.95 

Operating Systems 

INDEX"^ — This easy-to-use disk-operating and file man- 
agement system for 6800 microcomputers is fast. I/O devices 
are serviced by interrupt request. INDEX® accesses peripherals 
the same as disk tiles — new devices may be added without 
changing the operating system. Other features: unlimited 
number ol DOS commands may be added • over 60 system 
entry points • display only those files at or above user-specified 
file activity level • versions available for SWTP MF-68, Smoke's 

BFD-68 and Motorola's EXORciser*. Price $99.95 

MINIDOS-PLUSX® — An extension of the original 
MfNIDOS® for LFD-400'* mini-disk systems, MINIDOS- 
PLUSX^ manipulates files by six-character names. Supports 
up lo 31 files. Resident commands include Initialize, Save, 
Allocate, Load, Files (directory list), Rename and Delete. 
Supplied on 2708 ROM with a minidiskette that includes 
transient utilities such as Copy, Backup, Create, Pack and Print 

Directory. Price $34.95. 

PSYMON' 5 ' — Percom SYstem MONitor for the Percom 
single-board/SS-50-bus-compatible 6809 computer accom- 
modates user's application programs with any mix of peripher- 
als without modifying programs. PSYMON® also features 
character echoing to devices other than the communicating 
device, sophisticated register and memory dump routines and 

more. Price (on 2716 ROM) $69.95. 

WINDEX'" — Described in detail elsewhere on this page. 
Business Programs 

General Ledger — For 6800/6809 computers using Per- 
com LFD mini-disk storage systems. Requires little or no 
knowledge of bookkeeping because the operator is prompted 
with non-technical questions during data entry. General Ledger 
updates accounl balances immediately — in real lime, and will 
print tinancial statements immediately after journal entries. User 
selects and assigns own account numbers; tailors tinancial 
statements to firm's particular needs. Provides audit trail. Runs 
under Percom Super BASIC. Requires 24K bytes of RAM. 
Supplied on minidiskette with a comprehensive users manual. 

Price $199.95. 

FINDER™' — This general purpose data base manager is 
written in Percom Super BASIC. Works wth 6800/6809 com- 
puters using Percom LFD-400® mini-disk drive storage sys- 
tems. FINDER'-* allows user to define and access records using 
his own terminology — customize file structures to specific 
needs. Basic commands are New, Change, Delete, Find and 
Pack. Add up to three user-delined commands. FINDER plus 
Super BASIC require 24K bytes ol RAM. Supplied on minidisk- 
ette with a users manual. Price $99.95 

Mailing List Processor — Powerful search, sort, create 
and update capability plus ability to store 700 addresses per 
minidiskette make this list processor efficient and easy to use. 
Runs under Percom Super BASIC. Requires 24K bytes of RAM. 
Supplied on minidiskette with a users manual. Price $99.95. 
From the Software Works 
Development and debugging programs for 6800 nCs on disk- 
ette: 

Disassembler/ Source Generator $30.95 

Reloc'tng Disas'mblr/Segmented Text Gen $40.95 

Disassembler/Trace $25.95 

Support Relocator Program $25.95 

Relocating Assembler/ Linking Loader $55.95 

SmithBUG" (2716 EPROM) $70.00 

Circle 37 on inquiry card. 

'/2-Price Special on Hemenway Software! 

CP/68+ disk operating system $ 49.97 

STRUBAL+1: compiler $124.97 

EDIT68 text editor $ 19.97 

MACRO-Relocating Assembler $ 39.97 

Linkage Editor (LNKEDT68) $ 24.97 

Cross Reference utility $ 14.97 



'-Irademark of Percom Data Company, inc. 

* trademark of Motorola Corporation 
^Trademark of Hemenway Associates Company 

• "SmithBUG is a trademark of the Software Works Company 



This programmable 
processes display 
stantly in real-time. The Electric 
Window™ resides completely in 
main memory so control is ac- 
complished by direct MPU access 
to the character-store memory and 
display control registers. Peer at 
the screen and you look right into 
video display memory space while 
you input and manipulate text — 
an indispensable feature for effi- 
cient screen editing and word 
processing. The Electric Win- 
dow™. It's worth looking into. Fea- 
tures include: 

• Programmable CRT controller chip that 
provides extraordinary versatility in 
software control of horizontal and verti- 
cal formatting, cursor positioning, scrol- 
ling and Start/Reset functions. 

• A standard ASCII 128-unit ROM charac- 
ter generator which generates easy-to- 
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Text continued from page 58: 

each type of terrain is an integer multiple of the cost unit. 

The movement cost for any one square on the terrain 
map is considered to be the cost to enter the terrain area 
represented by that square. If you are currently in square 
X, and wish to move to square Y, then consider the cost 
of moving into square Y as the movement cost for square 
Y. The movement cost of square X, the current square, 
has no effect on the calculation; the movement cost is 
affected only by the nature of the terrain you are about to 
enter. 

The result of determining movement costs is a cost 
matrix, C, where C(IJ) is the movement cost of the ter- 
rain in the square in the I-th row and J-th column of the 
map. For all terrain which is effectively impossible to 
enter, or for which entrance is prohibited, C(/,/) =0 is 
assigned. 

The third step is to generate terrain masks. First deter- 
mine max, which is the maximum value found among all 
the movement costs in C. Then for all values k such that 
1 < k< C max you define the terrain mask T/c where Tk (/,/) 
is 1 if C(I,]) = k, and Tk(I,J) = otherwise. 

Now you should define a scatter function for the prob- 
lem. The function will produce scatter mappings for use 
with the terrain masks generated above. The input to this 



wwwwwwww 


blank 


= Clear 


WW R R WW 






W R R W 


R 


= Rough 


W R J J J W 






W J J J W 


J 


= Jungle 


W J WW 






W WWWW 


W 


= Water 



WWWWWWWW 

Figure 1: Map of a small island with clear, rough, and jungle ter- 
rain. The map is represented on a rectangular grid. 



function is a boolean array of starting positions (1, if yes; 
0, if no). The output is another boolean array of ending 
positions of moves of distance one from the starting posi- 
tions. Since distance is a factor, you must define a metric, 
or distance function, for this problem. 

Example of the Procedure 

In figure 1, there is a map of a small island with terrain 
of three types: clear, rough, and jungle. The map has 
been placed on an 8 by 8 rectangular grid, and each grid 
square is clearly identified as being a single type of ter- 
rain. 

Let us return to our hiker traveling cross-country on 
foot. Suppose that he requires 10 minutes to travel 
through one square of clear terrain, 20 minutes for rough 
terrain, and 30 minutes for jungle terrain. The terrain 
type "water" is effectively impassable in this problem. 
Thus, the movement cost is in terms of 10-minute periods 
of time, and you can construct the cost matrix C as 
shown in figure 2. Since 3 is the maximum movement 
cost value found in C, you will have three terrain masks: 
Tl, T2, T3 as shown in figure 3. 

Using a rectangular grid, there is a choice between two 
obvious distance functions with strictly integer values. 
The first distance function is the "city" metric, which 
defines the distance between points (a,b) and (c,d) as 
| « — c | + \b — d\ where |;c| is the absolute value of x. 
This function derives its name from the fact that in the 
rectangular system of streets found in a city, no move- 
ment is allowed diagonally through blocks. All distances 
are in terms of the net distance north or south added to 
the net distance east or west. 

The second distance function is the "square" metric, 
which defines the distance between points (a, b) and (c, d) 
as the maximum of \a — c\ and \b — d\. Its name is de- 
rived from the fact that the shape of the area containing 
all squares that are N or less units distant is a square, for 
any integer N. 



00000000 









2 


2 


1 


1 











1 


2 


2 


1 


1 


1 








1 


2 


3 


3 


3 


1 








1 


3 


3 


3 


1 


1 








1 


3 


1 


1 


1 











1 


1 


1 















00000000 
Figure 2: A movement cost matrix for the island map of figure 1. 



Scatter Functions 

Now it is necessary to define scatter functions CSC and 
SSC for the "city" and "square" distance functions, 
respectively. Let A be a matrix the same as C; that is, an 
8 by 8 matrix. Let A (J,/) = for all J and /, except for the 
one location on the map that is to be used as the starting 
position. A(/,/) will be 1 for the starting location. Matrix 
A is the input to the scatter function. B will be designated 
as the output matrix. The notation X(A) to represent the 
results of applying the function X to the matrix A will 
also be used. For the city distance function, the function 



00000000 


00000000 


00000000 


1 10 


1 10 


00000000 


10 1110 


1 10 


00000000 


10 10 


10 


1110 


10 110 


00000000 


1110 


10 1110 


00000000 


10 


1110 


00000000 


00000000 


00000000 


00000000 


00000000 


Tl 


T2 


T3 



Figure 3: The three terrain masks that will be superimposed on the movement cost matrix of figure 2. 



62 February I960 © BYTE Publications Inc 



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BYTE February 1980 


63 





10 


a. A 




10 
1110 
10 

b. CSC(A) 



10 
1110 

11111 

1110 
10 
c.CSC(CSC(A)) 




1110 
1110 
1110 

d. SSC(A) 



1111 
1111 
1111 
1111 
1111 

SSC(SSC(A)) 



Figure 4: Figure 4a is an example of a starting matrix, A. Figure 4b represents the matrix after the CSC (city) scatter function has been 
applied. The CSC function is then applied a second time to obtain the matrix in figure 4c. Figures 4d and 4e represent the results ob- 
tained after applying the SSC (square) scatter function to the matrix in figure 4a once and twice. 



CSC will assign to each element of B the value: 

B(/J) = CSC(A(/,/)) = A(/J) OR A(/,/+l) 

OR A(7J-1) 
ORA(/+l,/)OR A(/-1,J) 

where OR represents the logical OR operation. For the 
square distance function, the function SSC will assign to 
each element of B the value: 



In both cases, all matrix elements A(I,J) that lie outside 
the matrix A are to be Considered zero, such as A(0,0). 
Figure 4a gives an example of a 5 by 5 starting matrix, 
A. Figure 4b represents the result of applying the CSC 
function to that matrix. In figure 4c, the result of apply- 
ing CSC to the matrix in figure 4b can be seen. Figures 4d 
and 4e represent the matrices obtained after one and two 
applications of SSC to the matrix in figure 4a. 



B(/J) = SSC(A(/,/)) 



A(/,7) OR A(/,7 + l) OR A(/J-l) 
ORA(7+l,7) ORAU-1J) 
OR A(/+l,7+l) OR A(/+l,7-l) 
OR A(7-1J+1) OR A(/-l,7-l) 




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V 



Solving General Terrain Problems 

You now have everything needed to solve terrain prob- 
lems: a map with a grid and coordinate system, a move- 
ment cost matrix, a set of terrain masks, a matrix of start- 
ing positions, and a distance function with associated 
scatter function. 

These solutions will probe all possible paths, incremen- 
ting by one unit at a time until your resources are ex- 
hausted or your goal is reached. If you reach the goal 
before you run out of resources, the proposed journey is 
feasible; if you can reach the goal only after running out 
of resources, the proposal is not feasible. Furthermore, 
once a proposed journey is proven to be feasible, you can 
then retrace the path from the goal back to the starting 
position to determine an optimal solution to the prob- 
lem. 

Now reconsider the problem of the man walking on the 
island of figure 1. The city metric and the scatter function 
CSC will be used. Let the walker's starting point be the 
square (3,5) on the map in figure 1; that is the clear ter- 
rain in the third row and the fifth column. During the 
first 10 minutes the hiker will expend one unit of cost and 
can, therefore, move one square north to (2,5) or one 
square east to (3,6). The hiker cannot move south or west 
to (4,5) or (3,4) since he has not yet expended enough cost 
units. Figures 5 and 6a show his starting location matrix 
and his matrix of possible new locations after 10 minutes, 
since each of these positions requires only one more unit 
of movement cost. After another 10 minutes, the hiker 
can reach the clear terrain squares at (2,6) and (3,7) by 
moving from the squares reached after first 10 minutes. 
The hiker could also have reached the rough terrain 
square (3,4). This would be possible by moving west for 
20 minutes from the starting position at square (3,5). All 



64 February 1980 © BYTE Publications Inc 



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other moves are impossible due to either a lack of suffi- 
cient travel time, in the case of the jungle square (4,5), or 
the presence of impassable terrain, such as the water to 
the north. Figure 6b shows the possible new locations for 
the hiker after 20 minutes (two units of movement cost 
expended). 

After 30 minutes, the hiker has finally expended 
enough units of movement cost to go south from his 
starting position to the jungle terrain square (4,5). He can 
now also reach the rough terrain square (2,4) by traveling 
west for 20 minutes from the clear terrain square (2,5). 
Figure 6c shows the hiker's possible locations after 30 
minutes. 

From the above example, it should be clear that move- 
ment into terrain with a movement cost of k depends on 
the position of the object k movement cost units before. 
Refer to each iteration of the example above as a move. 
Also, designate the matrix of possible locations after k 
moves MA: or the /c-th scatter mapping. 

This relation can be expressed as follows: the new ter- 
rain squares of movement cost k that you can reach on 

00000000 

00000000 

00001000 M0 

00000000 

00000000 

00000000 

00000000 

00000000 

Figure 5: The starting matrix for the island problem with the 
traveler standing in the clearing at location 3,5. 



move n is represented by the matrix A where A(I,J) is 
equal to Tfc (/,/) AND B(/,/) where B = XSC (Mn-fc). 
(XSC is the scatter function. AND represents the logical 
AND operation.) From this you obtain the relation: 

Mn = Mn-l OR (Tl AND XSC (Mn-1)) 
OR (T2 AND XSC (Mn-2)) 



OR (Tk AND XSCQAn—k)) 

where k is the minimum of C m „ and n. In both of these 
relations, function XSC could be replaced by CSC, SSC, 
or any other scatter function to allow the use of any other 
metric or even another grid system, such as the hexagonal 
grid. The hexagonal grid will be discussed in part 2 with 
reference to conflict simulations. Figure 7 shows the scat- 
ter mappings Ml, M2 and M3 using the square scatter 
function, SSC. It is left to the reader to verify that this 
relation holds for both scatter functions. 

Using scatter maps, you can prove or disprove the 
feasibility of these proposals by determining whether this 
goal is a possible new location in the scatter mappings. 

Determining an Optimal Path 

Suppose that after n moves, the scatter map Mn finally 
contains the goal. Therefore, you know that there exists a 
path from your starting location to the goal which re- 
quires a movement cost of n, and you know that no less 
expensive path exists. To find this path it is necessary to 
first define the matrices S/c that are the sums of all the 



00000000 
10 
1 10 
00000000 
00000000 
00000000 
00000000 
00000000 
a. Ml 



00000000 
110 
11110 
00000000 
00000000 
00000000 
00000000 
00000000 
b. M2 



00000000 
1110 
11110 
10 10 
00000000 
00000000 
00000000 
00000000 
C. M3 



Figure 6: After 10 minutes, the traveler may be in any of three positions (figure 6a). Each of these positions represents a 10 minute or 
less expenditure of time. After another 10 minutes, the traveler may be in any of the squares indicated by figure 6b. Figure 6c 
represents squares where the traveler may be after 30 minutes. 



00000000 


00000000 


00000000 


1 10 


1110 


1110 


1 10 


11110 


11110 


00000000 


10 


11110 


00000000 


00000000 


110 


00000000 


00000000 


00000000 


00000000 


00000000 


00000000 


00000 000 


00000000 


00000000 


a. Ml 


b. M2 


C. M3 



Figure 7: The first, second, and third scatter-function mappings using the square scatter function (SSC) as defined by equations in 
text. 



66 February 1980 © BYTE Publications Inc 



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BYTE February 1980 67 



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00000000 

13 2 

00024320 

10 10 

00000000 S3 

00000000 

00000000 

00000000 

Figure 8: The third scatter sum using the city scatter function 
(CSC) for the island example. All moves which are made must 
conform to the city metric (distance function). 



scatter maps MO through Mk. Sk will be referred to as the 
fc-th scatter sum. Note that S0 = M0. Figure 8 shows the 
third scatter sum for the function CSC. 

The algorithm for finding an optimal path is as 
follows: beginning at your goal, follow a path of strictly 
increasing elements of Sn until you reach your starting 
position, choosing the most rapidly increasing path if 
more than one exists. Since all the possible locations in 
MIc are in M/c + 1, for all k, the more quickly a location is 
reached from the starting point, the higher its value will 
be in each scatter sum. 

For example, if the clear terrain square (4,7) was your 
goal, you would use the third scatter sum, S3, which is in 
figure 8. Following the movement restrictions imposed by 
the city function, you will consider only those locations 
given by the scatter of the current location to determine 
the next location on your path. Thus, you will choose 
your next location from the squares (4,8), (4,6), (5,7) and 
(3,7). 

Square (3,7) will be chosen, since it has the maximum 
value in S3. In the same manner, squares (3,6) and (3,5) 
will be chosen so that your optimal path from starting 
point to goal is (3,5) to (3,6) to (3,7) to (4,7). In the same 
manner, you can find that the optimal path from (3,5) to 
(2,4) is by way of (2,5). 

When you try to find the optimal path and there are, at 
some point between the goal and start, two or more 
possible locations from which to choose, you can ran- 
domly choose any one of them with equal success. This 
algorithm, therefore, will find an optimal path, but not 
necessarily the only such path. 

In Part 1 I have discussed some general terrain pro- 
blems and demonstrated a few solutions using a rect- 
angular grid. This method is very easy to implement with 
two-dimensional boolean arrays and lends itself well to 
most of the problems that will be encountered. One 
notable exception, however, is the conflict simulation or 
"war game." These games are usually played on terrain 
maps of a battlefield, upon which a grid of hexagons is 
superimposed. 

This hexagonal grid (or hex grid) resembles a honey- 
comb. It eliminates the need for two different metrics, 
since there are no diagonals, but it requires the definition 
of a new system of coordinates. 

In Part 2 I shall define this coordinate system, a 
distance function, and a scatter function. I shall also 
discuss the representation of specific terrain-related game 
features such as directional terrain (roads and bridges) 
and "no-exit" terrain (zones-of -control). ■ 



68 February 1980 © BYTE Publications Inc 



Circle 45 on inquiry card. 



mil iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiMi iiiiiiiiiiiiniiiiiiiiiiiiiiii iiiiiiimiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii 

BYTE News .... 

iiiiiiiiiiiiimiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiuiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiitiiiiiiiiiimiiiiiii 



VOICE-CONTROLLED CONSUMER PRODUCTS: At a recent electronics show in Japan, several 
Japanese manufacturers demonstrated voice-response and voice-activation of many consumer pro- 
ducts. Sanyo, Toshiba, Sharp, Sony, Hitachi, and Matsushita demonstrated a wide variety of con- 
sumer products that respond to oral commands. Using microprocessor-controlled speech analyzers 
and synthesizers, the processors controlled television channel selection, volume and color control, 
and operated video games and clocks. Some units talked back to confirm user commands. 

It is expected that many of these products will be commercially available in a year or two. Present 
technology allows registration of up to three persons in the voice- recognition circuit. Manufacturers 
agree that the voice recognition is not 100% perfect, but that it will be in time. 

SOME HOME COMPUTERS FAIL FCC RFI SPECS: The Federal Communications Commission 
(FCC) has released the results of their tests of personal computer systems for radio-frequency inter- 
ference (RFI). RFI has become an increasing problem to television and FM radio reception, similar 
to the citizen's band radio interference problem several years ago. The FCC has proposed as a stan- 
dard a radiation limit of 100 microvolts per meter at a 3-meter distance. 

Early last year the FCC tested the Radio Shack, Apple, Heath, Texas Instruments (TI), Com- 
modore PET, and Southwest Technical Products personal computers. Only the Texas Instruments and 
Commodore systems met the specification. Atari had submitted and passed the specification earlier. 

The standard goes into effect July 1, 1980, and all manufacturers have declared their intention to 
make necessary modifications to assure compliance with the specifications. 

CENTRONICS REVEALS NEW PRINTING METHOD: In a press conference held on November 13, 
1979, Centronics Data Corp of Hudson, New Hampshire, demonstrated a new method of printing on 
paper. A single stylus driven by voice coils through a parallelogram flexure mechanism presses a 
carbon ribbon against paper to form characters in almost the same way as people write using pens 
and pencils. Character fonts are switched by changing the controlling software; an almost infinite 
variety of symbols may be produced, including mathematical, Greek, Chinese, Cyrillic, and Arabic 
character sets. The prototype Quietwriter typewriter devices print with excellent quality at a speed 
of 17 cps for English-language character sets. Products using the Quietwriter mechanism may be 
sold beginning about the third quarter of 1981. 

NEW LISP SYSTEM: The LISP Co (T.(L.C)) of Los Gatos, California, has completed their first ver- 
sion of LISP for the Z80. It is a dialect of the MIT LISP-Machine LISP, complete with strings, I/O 
streams, Muddle's parameter-description mechanism, and comprehensive documentation. This ver- 
sion was done for a major personal computer manufacturer; (T.(L.C)) will soon announce their own 
version that will include hardware to support the LISP programming environment. 

HOBBYIST ELECTRONIC MAIL SYSTEM FORMING: Hobbyists are setting up a low-cost mail 
system using their microcomputers. This is possible using a $12 software package from the Personal 
Computer Network (PCNET) committee. With it, a personal computer owner can set up his machine 
to automatically dial another system or systems at a preset time (usually late at night), deliver 
messages, and return a status report (delivered or not delivered). 

Hobbyists are also setting up dial-in, free-access message systems for discussion purposes using 
the FORUM-80 software and Radio Shack TRS-80s. Three forums are already in operation: forums 
devoted to tracing family histories (in Fairfax, Virginia), information on engineering applications of 
microcomputers (Olathe, Kansas), and applications of microcomputers for the handicapped (Mem- 
phis, Tennessee). For more information on these applications, contact Jon Tara, c/o SEMCO, POB 
9578, Detroit MI 48202. 

COMPUTER COMPANIES GO INTO RETAILING: The latest computer stores are those set up by 
Digital Equipment Corp (DEC), IBM, and NCR. Following the innovative experiences in computer 
retailing established by Tandy Corp and independent stores, the traditional computer manufacturers 
have decided to meet the challenge head on. DEC already has in operation almost twenty "computer 
stores" where customers can sample the DEC small computers. However, the stores have no inven- 
tory and purchases are shipped from a distribution center. 

February 1980 © BYTE Publications Inc 69 



IBM now stocks their 5110 small business systems at fifty centers where a purchaser can get a 
system on a cash-and-carry basis. These centers were originally opened to demonstrate and train 
users, and then the retail operation was added. A typical system sells for $16,000. 

NCR has opened two pilot stores in Cincinnati to sell cash registers and small computers in the 
$15,000 price range. Data General is selling its MicroNOVA system through fifty independent 
dealers, and Texas Instruments is beginning computer demonstrations in its San Francisco store. 

With the cost of small business computer systems decreasing, the profit margin is no longer 
enough to support the high-cost selling techniques of large computer systems. 

MOTOROLA, TANDY AND WESTERN UNION INTRODUCE "GREEN THUMB" SYSTEMS: Spon- 
sored by a grant from the US Department of Agriculture, Motorola and Western Union will set up an 
experimental agricultural video-telephone information system known as Project Green Thumb. 
Tandy Corp will manufacture the terminals to be located in 200 farm homes in Kentucky. Farmers, 
via telephone lines, will be able to access weather, market, and agriculture data from remote com- 
puters. 

RANDOM NEWS: Atari has filed an appeal with the Federal Communications Commission (FCC) to 
stay the decision (reported in last month's BYTE News) in which the FCC granted Texas Instruments 
a waiver on permissible interference standards for personal computers. Atari feels that if other com- 
panies can pass the specification, then the TI request should not have been granted .... Texas 
Instruments will soon have competition in the voice synthesis area. National Semiconductor Corp 
and ITT Semiconductor are both showing samples of their new synthesizer parts. These integrated 
circuits are aimed at low-price consumer applications such as talking clocks, telephone-answering 
equipment and automobile warning devices .... Texas Instruments has introduced four new ter- 
minals that have dual-matrix print heads. The head prints two characters with each pass across the 
page enabling the unit to print 120 characters per second .... MIT (Massachusetts Insitute of 
Technology) has received a development contract worth several million dollars from Heath Co and 
Exxon Enterprises. The contract calls for the MIT Computer Science Laboratory to develop an 
advanced cartridge-disk-based 16-bit microcomputer system for use in office automation. Although 
initial plans called for MIT to use Zilog's 16-bit microprocessor, it is reported that they have switched 
to the Motorola 68000 to use memory more efficiently. Both Heath and Exxon will have nonexclusive 
manufacturing rights, and Exxon will have exclusive software rights .... Chuck Peddle, the 
developer of the 6502 microprocessor, the KIM-1, and PET computers, has a new product. It is the 
Commodore 4500 4-bit microprocessor. It represents a radical departure from the 6502 
architecture .... Researchers at Bell Labs announced the development of an improved elec- 
trochromic display using iridium. It consumes less power and could be cheaper to produce than 
light-emitting diode and liquid-crystal type displays. It does not have to be energized continuously 
and is pulsed to turn on and off. 

APOLOGY DUE: In the September 1979 BYTE News column, I reported on 16 -bit 8086 processor 
boards for S-100 systems. I regret that I omitted mention of a company that has been making such a 
board since December 1978. The company is Tecmar Inc, 23414 Greenlawn Ave, Cleveland OH 
44122. They sell a complete line of S-100 boards to make up a complete system. 

RANDOM RUMORS: Apple Computer will soon introduce the Apple III, and it is rumored that it 
will not use the 6502 microprocessor. Apple is keeping a tight lid on their plans (bit-slice, perhaps?) 
for this unit. . . .Digital Research, the firm that developed CP/M, the most popular disk operating 
system for microcomputer systems, will soon announce a version of CP/M for the Intel 8086 16-bit 
microprocessor, which will include an assembler program. . . .IMI (International Memories Inc) of 
Cupertino, California, the first company to ship 8-inch, Winchester-technology, hard disk drives, is 
rumored to be planning to show a 514 -inch, 3-megabyte Winchester drive at the 1980 National Com- 
puter Conference in June. Rumor is that there will be at least one other such drive shown at the 
NCC. . . . 

MAIL: I receive a large number of letters each month, as a result of this column. If you wish 
a response please include a stamped, self -addressed envelope. 

Sol Libes 

Amateur Computer Group of New Jersey (ACG-NJ) 

1776 Raritan Rd 

Scotch Plains NJ 07076 

70 February 1980 © BYTE Publications Inc 



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BYTE February 1980 71 - 




A Computer-Controlled 
Light Dimmer 

Part 2: Implementation 



John H Gibson 

Physics Department 

Alma College 

Alma MI 48801 




Photo 3: Close-up view of the Heathkit ET-3400 microprocessor trainer wired for use with the demonstration program. The ET-3400 
programmable timing module is connected to the trainer's data bus via the eight wires from the left corner of the picture. The syn- 
chronizing signal is transmitted over the yellow-black twisted pair at the bottom of the picture. The red-orange, red-white, and red- 
yellow twisted pairs carry the output trigger pulses to the three AC phase controls. 



The numbering of the photos, 
figures, and tables is continued 
from part 1 of this article, January 
1980 BYTE, page 56. 



In part 1 is an examination of the 
basic principles and techniques for 
achieving proportional AC phase 
control with a microcomputer and a 
programmable timer. I would now 



like to present a completely worked- 
out demonstration program designed 
to run on a Heathkit ET-3400 micro- 
processor trainer. This demonstration 
program will operate three lamp cir- 
cuits, giving you keyboard control 
over the lamps that are to be faded on 
and off. 

In addition to the ET-3400 trainer, 
you will need an MC6840 program- 
mable timer module, a 7405 hex in- 



verter (open collector), a syn- 
chronizer (from figure 5 in part 1), 
and three AC phase controls (each 
from the circuit of figure 9 in part 1). 
Here is a step-by-step procedure for 
making the demonstration program 
work: 

1) Plug the MC6840 and the 7405 in- 
tegrated circuits into the ET-3400 
trainer's breadboard socket. 



72 February 1980 © BYTE Publications lnc 



+5V FROM MICROCOMPUTER 



R2 

330ft 
1/4W 



TO _, 

MICROCOMPUTER <0 
MR<5 INPUT 




SYNCHRONIZER 



HI 



LO 



26 



ICS 
MC6840 



G3 



G2 



Gl 



03 



02 



01 



27 



Ih 



MICROCOMPUTER 
GROUND 



+ 5V FROM MICROCOMPUTER 
A 






-^ 



l_. 



IC3 
7405 



AC PHASE 
CONTROL #3 



AC PHASE 
CONTROL #2 



AC PHASE 
CONTROL*! 



JL 



_& 



M. 



<> — <3 



-* 120 VAC 
60 Hz 



LAMPS 



Number 

IC3 
IC5 



Type 

7405 
MC6840 



+5V GND 



14 
14 



Figure 10: Wiring diagram for proportional power control of three AC lamp circuits. Connections between the MC6840 program- 
mable timer and the ET-3400 microprocessor trainer have been omitted for clarity. ' 



2) Make the connections between the 
MC6840 and the ET-3400 trainer 
as shown in table 2. 

3) Wire the circuit shown in figure 10. 

4) Load the FADER2 program in 
listing 1 beginning at location hex- 
adecimal 0100. 

5) Memory location 0000 stores a 
minimum delay number for all 
lamps. If you want the lamps to 
reach maximum brightness, it 
should be preset to 00. 

6) Fading rates for the three lamps 
should be preset in memory loca- 
tions 0001, 0002, and 0003. Setting 
each of these rate values to hex- 
adecimal FF will cause each lamp 
to go from complete darkness to 
full brightness in about 2 seconds. 
At the opposite extreme, setting 
each rate value to 01 will cause this 
change to take 9 minutes. 

7) Location hexadecimal 017F con- 



Author's Note 

/ am indebted to Professor Kameswara Rao, 
of National Semiconductor. Santa Clara CA, 
for his advice and technical support. This lamp 
control program was developed and tested in 
his electronics laboratory at Western Michigan 
University with the use of a Motorola M6800 
cross-assembler resident on Western's PDP-10 
computer. 



tains the output-pulse-width value 
hexadecimal IE that was computed 
in part 1 of this article. This pulse 
width was computed for a 
microprocessor clock frequency of 
1 MHz. If your system's clock fre- 
quency is different, you will have 
to recompute this pulse width. 

A pulse width that is too short 
will not permit the lamps to darken 
completely; a pulse width that is 
too long will cause the lamps to 
flicker or flash back on at full 
brightness just when you expect 
them to be completely dark. 

8) The program ( listing 1, p. 74) 
begins execution at location hex- 
adecimal 0100, initializing all 
variable locations. With the pro- 
gram running, pushing keys thru 
7 will fade the lamps on and off in 
different combinations, according 
to the binary value of the keys 
pressed. The lamps' changing 
values will appear on the ET-3400 ! s 
six seven-segment readouts. 

9) You can stop the program without 
turning off the lamps by pushing 
the 9 (break) key. With the pro- 
gram stopped, you may examine 
and change registers, all without 
affecting the lamps. You may then 
restart the program at location 





6840 Pin 




6840 


Numbers 


ET-3400 


v„ 


1 


GND 


v„ 


14 


+ 5 V 


RESET 


8 


RST 


IRQ 


9 


no connection 


RS0 


10 


A0 


RS1 


11 


A1 


RS2 


12 


A2 


R/W 


13 


R/W 


CSO 


15 


A14 


CS1 


16 


A15 


Enable 


17 


4-2 


DO 


25 


DO 


D1 


24 


D1 


D2 


23 


D2 


D3 


22 


D3 


D4 


21 


D4 


D5 


20 


D5 


D6 


19 


D6 


D7 


18 


D7 



Table 2: Connections to be made between 
the Heath ET-3400 microprocessor trainer 
and the MC6840 programmable timer. 



hexadecimal 0110, which retains 
previous values in the variable 
locations. 

This demonstration program 
should be enough to fire your 
imagination to think of your own 
applications for this lamp control 
technique. I will be interested in hear- 
ing about programs and applications 
developed by BYTE readers. 



February 1980 © BYTE Publications Inc 73 



Listing 1: FADER2, a program written in assembler language for the Motorola M6800 processor to control the light dimmer. 

M T R D LA M 6 8 S A M C R S S •••• A S S M B L E R 

M 68S AM IS THE:: PROPERTY OF MOTOROLA SP.O- INC, 
COPYRIGHT .1.974 TO .1.975 BY MOTOROLA INC 

MOTOROLA M6800 CROSS ASSEMBLER r RELEASE 1,2 

"ADER2 



/ PRESET MINIMUM DELAY 

/ PRESET FADING RATE 1 
/ PRE: SET PAD TNG RATE 2 
/ PRESET FADING RATE 3 



0000.1. 








NAM 


F 


00003 


0000 






ORG 





00005 


0000 


000.1 


MINDLY 


RMB 


1 


00007 


0001 


000.1 


RATE! 


RMB 


1 


00008 


0002 


000.1 


RATE2 


RMB 


i 


00009 


0003 


0001 


RATE3 


RMB 


1 


0001.1 


0004 


000.1 


FINAL! 


RMB 


i 


00012 


0005 


000.1 


FINAL 2 


RMB 




00013 


0006 


0001 


FINAL 3 


RMB 




00015 


0007 


000.1 


DELAY 1. 


RMB 


1 


000 16 


0008 


0001 


DELAY2 


RMB 


1 


00017 


0009 


0001 


DEI...AY3 


RMB 


i 


000.1.9 


000 A 


0001 


INTER! 


RMB 


i 


00020 


00 OB 


0001 


INTER 2 


RMB 


i 


0002.1 


OOOC 


000.1 


INTER3 


RMB 


i 



00023 



OOF 7 



UIRQ 



EQU 



♦ OOF 7 



/ MONITOR VECTORS HERE ON IRQ 



00025 

00027 
00028 
00029 

00031 
00032 

00034 
00035 



* ADDRESSES IN PROGRAMMABLE TIMING MODULE 



8000 
8001 
8000 

800.2 
8003 

8004 
8005 



CR1 
CR2 
CR3 

Ml 
LI 

M2 
L2 



EQU 
EQU 
EQU 

EQU 
EQU 

EQU 
EQU 



♦ 8000 
CRlfl 
CR1 

CR.1.+2 
CRi+3 

CR.l+4 
CR1+5 



/ 
/ 



MSB 



OF LATCH 
OF LATCH 



/ MSB OF LATCH 2 
/ LSB OF LATCH 2 



00037 
00038 



8006 M3 EQU CR1+6 / MSB OF LATCH 3 

8007 L3 EQU CR1+7 / LSB OF LATCH 3 



00040 

00042 
00043 
00044 
00045 



FCOO 
FDF4 
FCBC 
ED7B 



* THESE ET-3400 MONITOR SUBROUTINES ARE USED 



RESET- 
INCH 
RED IS 



EQU 
EQU 
EQU 



DSP LAY EQU 



♦FCOO / RETURN TO MONITOR 

♦FDF4 / INPUT CHAR FROM KEYBOARD 

♦FCBC / RF SET DISPLAY TO 1ST LED 

♦FD7B / DISPLAY ROUTINE 



00047 



* MAKE A COLD START FROM THIS ADDRESS •■•■ ♦OlOO 

Listing 1 continued on page 76 



74 February 1980 © BYTE Publications Inc 






for 6800/6809 

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75 



Listing 1 continued: 

00049 0.1.00 



ORG 



$.100 



0005:1. 



* INITIALIZE DELAYS SO AIL LAMP'S ARE OFF 



00053 0:1.00 86 FF CLDSTR LDA A #$FF 

00054 0102 CE 0004 LUX #FINAl. 



/ MAXIMUM DELAY VALUE 
/ INITIALIZE POINTER 



00056 0105 A7 00 INITIA STA A 0?X / STORE #*FF HERE 

00057 0.1.07 08 I NX / POINT TO NEXT VARIABLE 

00058 0:1.08 SC OOOD CPX #INTER3+1 / LAST OAR I ABLE? 

00059 0.1. OB 26 E8 BNE INITIA / RETURN IE NOT DONE 



00061. 0.1. OD 01 

00062 0.1. OE 01. 

00063 0.1. OF 01. 



NOP 
NOP 
NOP 



00065 

00067 0110 OF 



* MAKE A WARM START PROM THIS ADDRESS - *0.l 10 
WRMSTR SEI / MASK IRQ WHILE INITIALIZING 



00069 
00070 
0007.1. 

00073 01.1.1 86 B6 

00074 0.1.13 06 B7 

00076 0115 B7 8000 
0007? 0.1.18 E7 8001 
00078 01 LB B7 8000 



* THESE STEPS CONFIGURE THE TIMERS EOR SINGLE -SHOT 

* OPERATION WITH TURN -ON DELAY M(LT1)T AND OUTPUT 

* PULSE WIDTH LT# 



LDA 


A 


#*B6 


LDA 


B 


#$B7 


STA 


A 


CR3 


STA 


B 


CR.2 


STA 


A 


CR1 



/ CONTROL WORD FOR CR3y CR1 
/ CONTROL WORD FOR CR2 

/ CONFIGURE TIMER 3 
/ CONFIGURE TIMER 2 
/ CONFIGURE TIMER 1 



00080 
0008.1 
00082 
00083 



* ON IRQ? THE ET-3400 VECTORS TO LOCATION 

* UIRQ, WE MUST PROVIDE A JUMP INSTRUCTION 

* AND A VECTOR TO TRANSFER TO OUR PROGRAM'S 

* IRQ SERVICE ROUTINE AT LOCATION tCYCLE. 



00085 01 IE 86 7E 

00086 0.120 97 F? 



LDA A #$7E 
STA A UIRQ 



/ LDA A WITH JUMP COMMAND 

/ STORE JUMP COMMAND AT UIRQ 



00088 0.122 CE 0.1.37 

00089 0125 DF F8 



LDX #CYCLE / JUMP TO THIS LOCATION 

STX UIRQ+1 / STORE #CYCLE AT UIRQ VECTOR 



0009.1 0127 OE CI... I 

00093 * MAIN PROGRAM LOOP 

00095 0128 BD PDF 4 KEY JSR INCH 



/ CLEAR IRQ MASK 



/ GET HEX VALUE OF KEY PUSHED 



00097 01 2B 81 09 

00098 01. 2D 26 04 



CMP A #$09 
BNE CONT 



/ IS IT "BREAK" KEY? 

/ BRANCH IE NOT "BREAK" 



00.1.00 012F OF 
00.1.01 0.1.30 7E FCOO 



SEI / SET IRQ MASK 

JMP RESET / GO TO ET-3400 MONITOR RESET 

Listing 1 continued on page 78 



76 February 1980 © BYTE Publications Inc 



rodna) 



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Listing 1 continued: 

00.103 0133 8D 09 CO NT BSR NEW FN / SET NEW FINAL VALUES 
00104 0135 20 Fl BRA KEY / GET NEXT CLOSED KEY VALUE 



00106 * IRQ INTERRUPT SUBROUTINE 

00108 0137 8D IE CYCLE BSR CHANGE / CHANGE DELAY VALUES 

00109 0:139 8D 3E BSE LOAD / LOAD TIMERS WITH NEW DELAYS 
00.110 01 3D SD 54 BSE SHOW / DISPLAY DELAY VALUES 

00.111 01 3D 3B ET.I 



00113 * SUBROUTINE TO CHANGE FINAL. VALUES 

00115 013E 81 07 NEWFN CMP A #*07 / VALID HEX VALUE? 

00116 0140 22 14 BHI NEWFN4 / BRANCH IF NOT VALID 

00118 014.2 CE 0004 LDX #FINAL 1 / POINT TO FINAL! 

00.120 0145 46 NEWFN 1 ROR A / SHIFT LAMP(X) BIT INTO 

00121 0146 24 04 BCC NEWFN2 / BRANCH TO DIM LAMP 

00123 0.148 D6 00 LDA B MINDLY / LDA B WITH MIN DELAY 

001.24 01 4 A 20 02 BRA NEWFN 3 

00126 01 4C C6 FF NEWFN2 LDA B #*FF / LDA B WITH MAX DELAY 

00128 014E E? 00 NEWFN3 STA B 0?X / STA B FINAL(X) 

00.130 0.150 08 I NX / POINT TO NEXT LAMP 

00131 0.151 SC 0007 CPX # FIN A I... 3+1 / LAST LAMP DONE? 

00132 0154 26 EE BNE NEWFN1 / RETURN IF NOT DONE 

00134 0156 39 NEWFN4 RTS 

00.136 * ROUTINE FOR CHANGING DELAY NUMBERS 

00138 0157 CE 0001 CHANGE LDX #RATE1 / POINT TO LAMP 1 

00.140 015A E6 09 CHNG1 LDA B 9 f X / LDA B INTER (X) 

00141 015C A 6 06 LDA A 6vX / LDA A DELAY CX> 

00143 015E Al 03 CMP A 3vX / CMP DELAY(X) WITH FINAL (X) 

00144 0160 22 08 BHI BRITER / BRANCH IF DELAY ( X ) >FINAL < X ) 

00145 0.162 27 OA BEQ RES TOR / BRANCH IF DELAY (X ) «FINAL ( X ) 

00147 0164 EB 00 DIMMER ADD B 0»X / B ~ INTER (X) + RATE(X) 

001.48 0166 89 00 ADC A **00 / A » DELAY fX) + CARRY 

00149 0168 20 04 BRA RESTOR 

00151 016A EO 00 BRITER SUB B ? X / B ^ INTER(X) - RATE(X) 

001.52 016C 82 00 SBC A #$00 / A « DELAY(X) •- BORROW 

00154 016E E7 09 RESTOR STA B 9vX / STA B INTERCX) 

00155 0170 A7 06 STA A 6vX / STA A DFLAY(X) 

00157 0172 08 INX / POINT TO NEXT LAMP 

00158 0173 80 0004 CPX #RATE3+1 / DONE WITH ALL 3 LAMPS? 

Listing 1 continued on page 80 
78 February 1980 © BYTE Publications Inc 



MioraHIET 

It's off and running. And delivering 

as promised. 



What is MicroNET? 

It is the personal computing 
service of CompuServe, 
Incorporated. CompuServe is a 
nationwide commercial time 
sharing computer network with 
large-scale mainframes. 
MicroNET allows the personal 
computer user access to 
CompuServe's large computers, 
software and disc storage 
during off-peak hours (from 
6 PM to 5 AM weekdays, all day 
on Saturdays, Sundays and 
most holidays). 

What do I get? 

You can use our powerful 
processors with X-Basic, 
Fortran, Pascal, Macro-1 0, AID 
or APL. You get 1 28K bytes of 
storage free (just access it at 
least once a month). Software 
includes games— including 
networking multi-playergames 
—personal, business and 
educational programs. 

In addition, there is the 
MicroNET National Bulletin 
Board for community affairs, 



for sale and wanted notices and 
the MicroNET Electronic Mail 
System for personal messages 
to other MicroNET users. You 
can even sell software via 
MicroNET. 

NEW! MicroQUOTE, a 
security information 
system for corporate 
stocks and public debt. 
NEW! MicroNET Soft- 
ware Exchange with 
dozens of new 
programs available for 
downloading to your 
personal computer at a 
specified charge. 
NEW! Executive pro- 
grams forTRS-80, Apple 
II and CP/M systems (so 
your machine and ours 
can talk to each other 
error-free). You can 
switch between terminal 
and local mode while 
on line. 

What do I have to have to 
use MicroNET? 

The standard 300 baud modem. 
MicroNET has local phone 



service in most major cities (see 
below) and a reduced phone 
charge in overa hundred others. 

What is the cost? 

We've saved the best for last. 
There is a one-time hook-up 
chargeof only$9.00! Operating 
time— billed in minutes to your 
VISA or MasterCharge card— is 
only$5.00an hour. 

Want more information? 

Good. Write to us at the address 
below. We'll send you a full 
packet of information about 
MicroNET. 

CompuServe 

Personal Computing Division 
Dept. B 

5000 Arlington Centre Blvd. 
Columbus, Ohio 43220 

MicroNET is available via local phone calls 
in the following cities: Akron, Atlanta, 
Boston, Canton, Chicago, Cincinnati, 
Cleveland, Columbus, Dallas, Dayton, 
Denver, Detroit, Houston, Indianapolis, 
Los Angeles, Louisville, Memphis, West 
Caldwell (NJ), New York, Philadelphia, 
Pittsburgh, San Francisco, Stamford (CT), 
St. Louis, Toledo, Tucson and 
Washington, D.C. 

Access to the MicroNET service is avail- 
able in 153 other cities for an additional 
charge of $4.00 per hour. 




. but the really impressive stuff is in the back room." 



Circle 49 on inquiry card. 



BYTE February 1980 



79 



Listing 1 continued: 








00.1.59 


0.176 


26 


E2 




001.61 


0178 


39 






00163 








* TH 


00.165 


0179 


CE 


8002 


LOAD 


00167 


01 7C 


96 


07 




00.168 


01 7E 


C6 


IE 




00.169 


0180 


A 7 


00 




00.1.70 


0182 


E7 


01 




00172 


0.184 


96 


08 




00173 


0186 


A 7 


02 




00174 


0188 


E7 


03 




001.76 


01 8 A 


96 


09 




00177 


01. 8C 


A 7 


04 




00.1.78 


018E 


E7 


05 





BNE 



RT 



CHNG1 



/ RETURN TO DO NEXT LAMP 



ROUTINE LOADS THE TIMER LATCHES 



LDX 



♦ Ml 



LDA A DEI...AY1 

I... DA B #$1E 

STA A OvX 

ST A B 1. y.X 

LDA A DEI...AY2 

STA A 2vX 

STA B 3vX 

LDA A DELAY3 

STA A 4?X 

STA B 5»X 



/ POINT TO Ml 



/ OUTPUT PULSE WIDTH 

/ LOAD Ml WITH DELAY 1 

/ LOAD LI WITH PULSE WIDTH 



/ LOAD M2 WITH DELAY2 

/ LOAD L2 WITH PULSE WIDTH 



/ LOAD M3 WITH DELAY3 

/ LOAD L3 WITH PULSE WIDTH 



00180 0190 39 



RTS 



00182 






* TH 


00.183 






* TH 


001.85 


0191 


BD 


FCBC SHOW 


001.86 


0194 


CE 


0007 


001.87 


0197 


C6 


03 


00.1.88 


0199 


BD 


FD7B 



5 ROUTINE SHOWS THE THREE DELAY VALUES ON 
ET-3400'S SIX 7 -SEGMENT READOUTS ♦ 



JSR PEDIS 

LDX #DELAY1 

LDA B #03 

JSR DSP LAY 



/ RESET DISPLAY TO 1ST LED 

/ START DISPLAY WITH DELAY1 
/ DISPLAY 3 BYTES 
/ DISPLAY DELAY 1 r 2 AND 3 



001.90 0.1 9C 39 



RTS 



001.92 



END 



SYMBOL TABLE 



MINDI../ 

final; 
inter: 

CR2 
I... 2 

RED IS 
KEY 

newfn: 

DIMM El 
,.>TOP -■ 



0000 
0005 
000 A 
8001. 
8005 
FCBC 
0128 
01.4C 
0.164 



RATE1 
FINAL 3 
INTER 2 
CR3 
M3 

DSP LAY 
CONT 
NEWFN3 
BR ITER 



000.1 
0006 
OOOB 
8000 
8006 
F.D7B 
01.33 
01 4E 
0.1 6 A 



RATE2 
DEL AY 1 
INTER 3 
Ml 
I... 3 

C LB SIR 
CYCLE 
NEWFN 4 
RE ST OR 



0002 
0007 
00 OC 
8002 
8007 
0100 
0137 
0156 
016E 



RATE 3 

DELAY2 

UIRQ 

I... 1 

RESET 

INITIA 

NEWFN 

CHANGE 

LOAD 



0003 
0008 
OOF 7 
8003 
FCOO 
0105 
013E 
0157 
0179 



F.TNAL1 

DELAY3 

CR1 

M2 

INCH 

WRMSTR 

NEWFN 1 

CHNG1 

SHOW 



0004 
0009 
8000 
8004 
FDF4 
0110 
0.145 
015A 
0191 



80 February 1960 © BYTE Publications Inc 



Now... 
You, the small systems user can enjoy 

the advantages of HI -performance 
l„0 c^ computer graphics 



PAT) Digitizers 




The perfect small system output device The perfect small system Input device 



Displays data in easy to read 

graphical format 

Both serial and parallel Inputs 

built-in. 

Used standard 8'/»" x 11" paper 

(DIN A4) 

Plotting speed up to 2.4 ips (60 

mm per sec) 



Resolution and repeatability of 
0.005 In. {0.1 mm) 
Origin is completely relocatable 
RS232C and 8 bit parallel inter- 



face 



;o (.?./■ 



J 



V 



V 



*^ 



For complete information contact 
Houston Instrument, One Houston 
Square, Austin, Texas 78753. 
(512)837-2820. For rush literature re- 
quests persons outside Texas call 
toll free 1-800-531-5205. In Europe 
contact Houston Instrument, 
Rochesterlaan 6, 8240 Gistel 
Belgium. Phone 059/27 74 45. 



DIVISION OF MUKK&iDMIjQ 



'the graphics - recorder company" 



HIPLOT ■ Circle Inquiry #232 
HIPAO - Circle Inquiry #233 

if Houston Instrument 





Programming DeicMes 



Gasuse 



Mike R Firth, 4712 Northway Dr, 
Dallas TX 75106 

Gasuse is a program I wrote to use 
facts I record in a notebook in my car 
to produce useful information. I note 
the mileage of my car, the cost of the 
gas, and usually the gallons and dol- 
lars of the purchase along with the 



state of purchase and date (for tax 
purposes). Aside from the special 
features noted below, the program in 
listing 1 consists of the initialization 
routine (lines 1010 thru 1084), the 
main loop (1100 thru 1900), and rou- 
tines to allow for missing information 
(2000 thru 2190) and printer output. 
The main loop continues until is 
entered for the miles. The program 
does not permit entering a lower 



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% 



-±- 



■ 



mileage than the last mileage reading. 
The missing information section will 
permit computations if two of the 
three items — price, gallons, cost — 
are known. 

The information printed out 
includes the entered (or calculated) 
numbers — miles at purchase, dollars, 
gallons — then two figures for this 
step — miles since last fill and miles 
per gallon. Then there are total 
figures — miles since start of trip and 
mileage since the start in terms of 
total dollars and total gallons. The 
total miles and mileage are figured 
anew at each step to smooth out 
errors. 

Notes on odd items: lines 40 and 50 
save retyping the commands used on 
the Wang for disk storage. U$ con- 
tains the character to move the cursor 
up one line. This results in the display 
being solid information, neatly 
arranged, with data entered on the 
bottom lines. The Select Print 
statements after line 8100 are the 
means of assigning the printed out- 
put. Only one device can be selected 
at a time, where 005 is the video ter- 
minal and 215 is the fast printer. Lines 
9400 thru 9406 are special functions 
that relate to special keys on the ter- 
minal and permit controlled listing of 
the program. Wang uses % for image 
statements, where most BASICS use : 
in my experience. 

Table 1 is an example output from 
listing 1. (See table 1 and listing 1 on 
page 124.) Please note that while two 
of the segment mileage figures vary 
considerably (17.9 and 40.1), the 
average mileage stays in the mid- 
twenties. One reason that segment 
mileage will vary is that the tank is 
not filled to the same point each time. 
If 10 gallons are used in 250 miles, but 
only 5 are purchased the program will 
give twice the mileage for that seg- 
ment. However, when one has to fill- 
up with 10 gallons after only 125 
miles, the mileage will drop. 

Note that the totals are run up each 
time the program is run, which repre- 
sent a page in your notebook — all the 
gas purchased on a trip or a month's 
driving. To add to a list, simply take 
the old list's starting mileage and the 
final totals as the first entry, (see table 
1 for example). 



82 February 1980 © BYTE Publications Inc 



Circle 51 on inquiry card. 



CP/M * VERSION 2 FOR TRS-80* MODEL II NOW AVAILABLE 



All Lifeboat programs require CP/M, unless otherwise stated. 



DIGITAL RESEARCH 

□ CP/M FLOPPY DISKETTE OPERATING SVS- 

" TEM — Packages supplied on diskette complete with 
B060 assembler, text editor. B080 debugger and various 
utilities plus IUI documentation. CP.'M available con- 
liguied lor most popular computer/disk systems includ- 
ing North Star Single. Double or Quad density. Allair 8" 
disks. Helios II. Exidy Sorcerer. Vector MZ, Heath HJ7t 
orH89t. TRS-SOt. 'COM 3712 and iCOM Micro Disk 
plus many other configurations available off Iho shelf 

S145/S25 

CP'M version 2 [not all (ormats available immediately) 

S170 S25 

D MP/M* $300 $50 



D MAC- 



ut^s** 1 - 



Macro Assembler Full Intel macro delmi- 
. Pseudo Ops include RPC. IRP. REPT, TITLE, 
PAGE, and MACLIB. Z80 library included. Produces Intel 
absolute hei oulput plus symbols file for use by SID (see 
below) SB5iS15 

D SID — 8080 symbolic dobuggor Full trace, pass count 
and break-point program testing system with back-trace 
and histogram utilities When used with MAC. provides 
full symbolic display of memory labels and eauated val- 
ues $70515 

□ ZSID- As above lor Z80 Requires 280 CPU SB5S2S 

D TEX — Text lermatier to create paginated, page-num- 
bered and [ustified copy from source text dies, diroctable 
to disk or printei . $ 70 $ 1 5 

D DESPOOL — Program to permit simultaneous printing 
ol data Irom disk while user executes another program 
Irom the console $45 $5 



Qtt' 



W5 



S300 S25 



!5'$25 



u 



MICROSOFT 

D BASIC-80 - Disk Extondod BASIC. ANSI compatible 
■ l. with long variable names. WHILE/WEND, chainini 
u able longih Me records , 

□ BASIC COMPILER - Language compatible with 
iv BASIC-80 and 3-10 times faster execution. Produces 
lis, slandard Microsofl relocatable binary output. Includes 

Macro-80. Also linkable lo FORTRAN-80 or COBOL-80 
code modules $3M/$25 

□ FORTRAN-80 — ANSI 66 (excepl for COMPLEX) 
v plus many extensions. Includes relocatable object com- 
& pilar, finking loader, library with manager. Also includes 

MACRO-80 (see below) $400, $25 

LJ COBOL-80 — Level i ANSI 74 standard COBOL plus 
© mosl ol Level 2. Full sequential, relative, and indexed file 
.a, support wilh variable die namos STRING, UNSTRING. 
COMPUTE, VARYING/UNTIL. EXTEND. CALL. COPY. 
SEARCH, 3 -dimensional arrays, compound and ab- 
breviated conditions, nested IF Powerful interactive 
screen-handling extensions Includes compatible as- 
sembler, linking loader, and relocatable library mana 

as described und=r MACRO-80 $623/$ 

MACRO-80 — 8080780 Macro Assembler. Intel and 
(£j Zilog mnemonics supported. Relocatable linkable output. 
6 Loador. Library Manager and Cross Reference Lisl 
utilities included $149,'$ 15 

□ XMACRO-86-8086 cross assembler. All Macro and 
(T, utility features ol MACRO-80 package. Mnemonics 

slighily modified Irom Intel ASM86 Compatibility dala 
sheet available $275 $25 

□ EDIT-80 — Very fast random access text editor for text 
© with or wilhout lire numbers Global and inlra-line com- 
mands supported. File compare utility included S89/S15 

MICRO FOCUS 

D STANDARD CIS COBOL - ANSI 74 COBOL 
a standard compiler fully validated by U.S. Navy tests to 
ANSI level I Supports many features lo level 2 including 
dynamic loading of COBOL modules and a lull ISAM die 
facihty Also, program segmentation, interactive debug 
and powertul interactive extensions lo support protected 
and unprotected CRT screen tormattmg Irom COBOL 
programs used wilh any dumb terminal $8 50/ $50 

□ FORMS 2 — CRT screen editor. Output is COBOL data 
X descriptions lor copying mlo CIS COBOL programs. 

Automatically creates a query and update program ot in- 
dexed dies using CRT protected and unprotected screen 
formats. No programming expenence needed. Output 
program directly compiled by CIS COBOL (standard) 
$200 -$20 

□ HDBS — Hierarchical Data Base System, CODASYL 
ononled wilh FILEs SETs. RECORDS and ITEMs which 
are all user defined. ADD, DELETE. UPDATE, SEARCH, 
and TRAVERSE commends supported. SET ordering is 
sorted. FIFO, UFO; next or prior One to many set rela- 
tionship supported. Read Wnlo protection at the FILE 
level. Supports FILEs which extend over multiple floppy 
or hard disk devices. 

□ MDBS — Micro Data Base Sy3iem. Full network data 
base wilh all lealures of HDBS plus multi-level Read/ 
Wnle protocdon lot FILE, SET, RECORD and ITEM. 
Explicit representation o) one lo one, one to many, many 
to many, and many lo ono SET relationships. Supports 
mulliple ownor and mulliplo record types within SETs. 
HDBS files are full/ compatible. 

G MDBS-DRS — MDBS will Dynamic Restructuring Sys- 
tem option which allows altering MOBS data bases when 
new ITEMs. RECORD!, or SETs are needed without 
changing existing dala. 

HD8S-Z80 version S20O/S35 

MDBS-Z80 version $7BO/$3B 

MDBS-0RS-Z80 version SBS0/S35 

8080 Version available at S75. extra. 

Z80 version requires 20K RAM. 8080 version requires 
24K RAM. (Memory requirements are additional lo CP/M 
and application program.) 

When ordering HDBS or MDBS please Specify ilthe vei- 
sion required is lor 1) Microsofl L80 i.e FORTRAN-80, 
COBOL-80. BASIC COMPILER. 2) MBASIC 4. XX. or 3) 
BASIC-80 5 



# 



C<p^^- 



£ „, 



EIDOS SYSTEMS 

D KISS — Keyed Index Sequential Search. Offers com- 
(i) piete Mulli-Keyed Index Sequential and Direct Access die 
management Includes burl-in utility functions tor 16 or 
32 bit arithmetic, string integer conversion and string 
compare. Delivered as a relocatable linkable module in 
Microsoft format for use with FORTRAN-80 or COBOL- 
80. elC S335 $23 

D KBASIC — Microsoft Disk Extended BASIC with all 

E0 KISS facilities, miograted by implementation ol nine 

additional commands in language. Package includes 

KISS.REL as dosenbod above, and a sample mail lisl 

program $505 $45 

To licensed users ol Microsofl BASIC-80 1MBASIC1 
J435S45 



>32S^' 



MICROPRO 

D SUPER-SORT I — Sort, merge, extract utility as abso- 

© lute executable program or linkable module in Microsofl 

,u lormat. Sorts dxed or vanabe records with data in binary, 

BCD, Packed Decimal. EBCDIC, ASCII, floaimg. fixed 

point, exponential, lield (ustilied. etc etc Even variable 

number ol Nelds per record! $225 $25 

□ SUPER-SORT II — Above available as absolute pro- 
;Bi© gramonly S175S2S 

D SUPER-SORT III - As II without SELECT, EXCLUDE 

<9® S125S25 

LJ WORD-STAR — Menu d-iven visual word processing 

© system lor uso wilh standard terminals. Text formatting 

iii) performed on scroon. Facilities lor text paginate, page 

number, juslily. conlor and underscore. User can pnnl 

one documeni while simullaneously editing a second. 

Edit facilities include global search and replace, read' 

write to olher loxi tiles, block move, etc. Requires CRT 

terminal wilh addressable cursor positioning $445/$25 

D WORD-STAR/MAIL-MERGE - As above wilh op- 

<o don for production mailing of personalized documents 

i*i wilh mail list Irom Dala-Slar or NAD $375/$25 

D WORD-STAR Customization Notes — For 
sophisticated users wtio do not have one of the many 
standard terminal or printer conliguralions in the distribu- 
tion version ot WORD-STAR HA 51 oo 

□ WORD-MASTER Texl Editor — In one mode has 
© superset ot CP'M's EO commands including global 
® searching and replacing, forward and backwards in die In 

video mode, providos lull screen editor lor users with 

serial addressable- cursor lermmal $125 $25 

Q DATASTAR — Ptotessional forms conlrol entry and 

»v display system lor koy-lo-disk data capture Menu driven 

" with built-m learning aids- Inpulliefd venlicaiion by length, 

mask, attribute (i e. uppercase, lowercase, numeric, auto 

dup.. etc). Buill-fn amnmetic capabilities using keyed 

data, constants and derived values Visual feedback tor 

easo ol forms design. Files compatible with all CP'M- 

MP/M supported languages'. Requires 32K CP/M 

S3 50 -S3 5 

D CBASIC-2 Disk Exlended BASIC — Non-interactive 
(Mi BASIC with psoudo-codo compiler and runlime interpre- 
ter. Supports lull lile contra 1 , chaining, integer and e 



tended precision variables, eic. 



$109 515 



D PASCAL/M — Compiler generates P code from ex- 
© (ended language implomeniaBon of slandard PASCAL. 
Supports overlay slmcture tnrough additional procedure 
ivill-j and Hi" SI.'OMi'Ni proc-jOuic lypo Provides con- 
venient siring handling capability with Iho added variable 
type STRING. Untyped dies allow momory image I/O. 
Requires 56K CP/M $350/$30 



D PASCAUZ - 280 r 

® ~ 



) code PASCAL compiler 



Produces optimized. ROMable re-entrant code. All i 

lacing lo CP/M is through ire support library The pack- 
age includes compiler, companion macro- assembler and 
source lor Iho library. Requires 56K and Z80 CPU. 
Version 2 Includos all ol Jensen'Wirlh excepl variant re- 
cords S275 S25 

Version 3 Upgrade with variant records and strings ex- 
pected 2/80 $395 $25 

□ PASCAL/MT — Subset ol slandard PASCAL. Gen- 
9 e'aies ROMable 8080 machine code Symbolic debugger 
(?) included. Supports interrupt procedures and BCD anlh- 

mel'c lor real variables. CP.'M die 10 and assembly lan- 
guage interlace supported. Lacks Sets. Enumeration and 
Rocord data types. Manual explains BASIC lo PASCAL 

conversion. Requires 32K $9S/$30 

Source lor PASCAL/MT run time package Requires 
MAC. (See undor Digital Research.) $50 

STRUCTURED SYSTEMS GROUP 

D GENERAL LEDGER- Interactive and tlexiWe sys- 
tem providing proof ant) report outputs Customization 
of COA created interactive!^ Multiple branch account- 
ing centers Extensive checking performed at data 
entry tor prool. COA correctness, etc Journal entries 
may be batched prior to posting Closing procedure 
automatically backs upmpu! files. Now includes State- 
ment Ol Changes in Financial Position Requires 

CBASIC-2 S099 525 

□ ACCOUNTS RECEIVABLE - Open Hem system 
wilh oulput lor internal aged reports and cuslomer-ori- 
enled stalemenl and billing purposes On-Line Enquiry 
permits mlormalion lor Customer Service and Credit de- 
partments. Interlace lo General Ledger provided if Oolh 
systems used. Requires CBASIC-2 $699 $25 

D ACCOUNTS PAYABLE - Provides aged state- 
ments ol accounts by vendor with check writing for 
selected invoices Can be used alone or wilh General 
Ledger and/or wilh NAD. Requires CBASJC-2$699/$25 
Prices and specifications subject to change wrthoul notice 



€<t- 



Shopping 
List No. 9 

Software for most popular 8080IZ80 computer disk systems including 
NORTH STAR, iCOM, MICROPOUS, DYNABYTE DB8/2 & DB8I4, EXIDY 
SORCERER, SD SYSTEMS, ALTAIR, VECTOR MZ, MECCA, 8" IBM, 
HEATH H17& H89, HELIOS, IMSAI VDP42 & 44, REX, NYLAC, 
INTERTEC, VISTA V80 and V200, TRS-80 MODEL I and MODEL II, 
ALTOS, OHIO SCIENTIFIC and IMS 5000 formats. 

1u ThB Software Supermarket is a trademark of Lifeboat Associates 




D INVENTORY CONTROL SYSTEM - Performs 

control functions ol adding and depleting slock ilems. 
adding new items and deleting old ifems. Tracks quantity 
ol items on hand, en order and back-ordered Optional 
hard copy audit trail « available. Reports include Master 
Horn Lisl, Slock Activity. Stock Valuation and Re-order 
Lisl Requires CBASIC-2 and 48K CP/M . S44SS25 

□ ANALYST — Customized dala entry and reporting sys- 
tem User specilies up lo 75 dala items per record Inter- 
active data entry, retrieval, and uadate laciMy makes 
information management easy. Sophislicaled report 
generator provides customized reports using selected 
records wilh mulliplo level broak-poinls lor summanza- 
lion. Requires CBASIC-2. 2<t x 80 CRT, printer and 48K 
system $225/$1 5 

D LETTERIGHT — Program to creale. edit and lype loi- 
ters or olher documenis. Has facihles lo enter, display, 
doloto and move text, with good video screen presenta- 
tion. Designed lo integrate with NAD for form loiter mail- 
ings, Requires CBASIC-2 $1 79/525 

D NAD Name and Address selection system — interactive 
mail lis! croation and maintenance arogram with outpul 
as lull reports with relerencu dala cr restricted mlorma- 
lion for mail labels. Transler system lor exlraclion and 
transfer ol selected records to creale new files. Requires 
CBASIC-2 $79/$20 

D QSORT — Fast sortmerge program tor files with fixed 
record length, variable field length information. Up to live 
ascending or descending keys. Full back-up ol input tiles 
created $95/$20 

GRAHAM-DORIAN SOFTWARE SYSTEMS 

□ GENERAL LEDGER — An on-line system: no batch- 
® ing is roquired. Entries to olher GRAHAM-DORIAN ac- 
iui counting packages aro automatically posted. User estab- 
lishes customized CO. A. Provides transaction rogisler, 
record ol |ournal entries, trial balances and monlhly clos- 
ings. Koops 1 4 monlh hislory and provides comparison of 
curronl year wilh previous year. Requires CBASIC-2. 
Supplied in source S495S35 

D ACCOUNTS PAYABLE — Maintains vendor lisl and 

S3 chock rogisler. Performs cash Mow analysis. Flexible — 

im;, writos chocks to specilic vendor lor certain invoices or 

can make partial payments. Automatically posls lo 

GRAHAM-DORIAN genoral lodgor or runs as stand alone 

system. Requires CBASIC-2. Supplied in source. 

S495 $35 

D ACCOUNTS RECEIVABLE - Creates trial balance 
® reports, prepares statements, ages accounts and records 
■.Si invoices. Provides complete mlormalion describing cus- 
tomer payment activity. Reccipls can Oe posted lo differ- 
ent ledqer accounts. Entries autcmatically update 
GRAHAM-DORIAN general lodger or runs as stand alone 
system. Roquires CBASIC-2 Supplied in source. 
S495 S35 

□ PAYROLL SYSTEM — Maintains employee masler 
i, file. Computes payroll withholding lor FICA. Federal and 
a Stale laxes Prints payroll register, checks, quarterly re- 
ports and W-2 iorms. Can generate ad hoc reports and 
employee lorm letters wilh mail labels. Requires 
CBASIC-2. Supplied in source code $49 5 $3 5 

D INVENTORY SYSTEM - Captures stock levels, 

(C) cosls, sources, sales, ages, turnover, markup, elc. 

tu'i Transaclion informalion may bo entered lor reporting by 
salesman, lypo of sale, date ol sale, etc. Reports avail- 
able both for accounting and decision making. Requires 
CBASIC-2, Supplied in source code $49S/$35 

ID JOB COSTING — Designod lor general conlractors. 

© To bo used interactively with other GRAHAM-DORIAN 



D APARTMENT MANAGEMENT SYSTEM - Fi- 

S nancial management system for receipts and security 
mj deposits ol apartment projects Captures dala on vacan- 
cies, revenues, elc. lor annual trend analysis. Daily report 
shows lalo renls. vacancy notices, vacancies, income 
lost through vacancies, etc. Requires CBASIC-2. Sup- 
plied in source code S49 5 S3 5 

□ CASH REGISTER — Maintains files on daily sales. 

'5 Files dala by sales person and item. Tracks sales, over- 

U rings, rolunds. payouts and total nel deposits, Requires 

CBASIC-2. Supplied in source code $495/$35 



U tiny C — Interactive interpretive system lor teaching 

(x) slruclurod programming techniques. Manual includes lull 

source listings $75,540 

□ BDS C COMPILER — Supports most major features 
# of language, including Siructures, Arrays. Pointers. 
reeursivo function evaluation, linkable with library to 80B0 

binary outpul. Lacks dala initialization, long & float type 
and sialic & register class speciliers, Documentation in- 
cludes "C" Programming Language book by Kernighan & 
Ritchie $11'0/$15 

□ WHITESMITHS C COMPILER - The ultimate in 

© syslems sollware tools. Produces laster code Irian Pas- 
(?) cal wilh more exlensiue facilities. Conforms to Iho lull 
UNIX*" Version 7 C language, described by Kernighan 
and Ritchie, and makes available over 75 lunctions for 
performing I'O. siring manipulation and storage alloca- 
tion. Linkablo 10 Microsoft REL files. Requires 60K CP/M 

S630 530 

D POLYVUEV80 — Full screen editor lor any CRT wilh 

® XY cursor positioning. Includes vertical and horizontal 

scrolling, inter active search and replace, automatic texl 

wrap around lor word processing, operations lor manipu- 

laling Clocks ollext, and comprehensive 70 page manual. 

$1 35/$1 5 

D POLYTEXT/80- 

:>«< applications Justifies and pagm 

generate lorm loiters wilh custom fields and conditional 
processing. Support lor Daisy Wheel pnnters includes 
variable pilch |ustificalion and molion optimization. 
$B5/$1 5 



ALGOL-60 — Powerlul block-slructured language 
compiler featuring economical run lime dynamic alloca- 
tion ol momory. Very compact (24K total RAM) syslem 
implementing almost all Algol 60 report fealuros plus 
many powerful extensions including string handling direct 
disk address I/O etc. Requires Z80 CPU . . . $199/$20 

' CPIM is .1 trademark ol Dirjltal Research. 

■2,80 is a trademark ol Zilog, Inc 

■UNIX is a trademark of Bell Laboratories. 

"WHATSIT? is a trademark ol Computer Headware 
Electric Pencil is a trademark of Michael Shrayer Software. 
* TRS-80 is a trademark of Tandy Corp 

tCPM loi Heath. TRS-80 Model 1 and PoyMoiphc 8B13 are 
modilied mid musl use specially compiled versions ol syslem 
and applications sollware 

ffi) MDiMii.'il viTMun .iwiilable lor use Willi CP M as 1 mpl mm 'iited 

on Heath and TRS-80 Model I compulers 



n Z80 DEVELOPMENT PACKAGE - Connsts of 
'" (1) disk die line editor, wilh global inter and mlra-line facili- 
ties; (2) Z80 relocating assembler. Zilog Moslek mne- 
monics, conditional assembly and cross relerence table 
capabrlilies; (3) linking loader producing absolute Intel 

hex disk file $95$20 

D 20T-Z80 Monitor Debugger lo break and examine 

lit, registers with siaiiriar^Zilotr-'Mostck mnemonic dis. t:. 

sembly displays S3S when ordered with ZHO Develop 

rnent Package $50 S10 

□ DISTEL — Disk based disassemble; to Inisl 8080 or 
TDL/Xitan ZOO source code, listing and cross relerence 
liles. Intel 01 TDL/Xilan pseudo ops oplional. Runs on 
8030 $65/S10 

D DISILOG — As DISTEL lo Ziloq Moslek mnemonic 
W dies. Rjns en Z80 only .... „..«.- S65S10 

D XASM-68 — Ne-rwuaco Cfg.-.s-.isse-iL"tr- « in nested 
conditiora's and luu Jaime ol osci-io jctvai.o's Assem- 
bles Iroms^ardaifl Maico j MCf^Cn .-i-i<cicrics lo Intel 
no* >*vfc.|'\^ S200/$25 

□ XASM-65 ■ Ah XASM.'tiB "v Mtjs I.-: '-nology 
MCS6S0O mnem^ffll §»** S200JS25 

D TEXTWRITER III — Text formatter lo justily and pagi- 
m nale letters and olher documents Special leatures in- 
clude insertion ol text during execution Irom olher disk 
dies or console, permitting recipe documents lo be 
created Irom linked fragments on other liles. Has facilities 
lor sorted index, table ol conlents and footnote insertions 
Ideal for contracts, manuals, elc. Now compatible wilh 
Eleclric Pencil prepared files. S125/S20 

Cl POSTMASTER — A comprehensive package lor mail 

"*' lisl maintenance. Features include keyed record exlrac- 
lion and label production. A form loiter program is in- 
cluded which provides neat letters on single sheet or con- 
tinuous Iorms. Requires CBASIC-2 S150-$15 

LJ WHATSIT?**** Interactive dala-baso system using 
associative lags lo retrieve information by subject. Hash- 
ing and random access used for fast response. Requires 
CBASIC-2 $1 25 525 

D XYBASIC Interactive Process Conlrol BASIC — Full 
disk BASIC features plus unique commands :o handle 
bytes, rotaie and shift, and lo tesl and sel bits. Available 
in Integer. Extended and ROMable versions, 

Inleger Disk or Integer ROMable S295 525 

Exlended Disk or Extended ROMable . S395 $25 

LJ SMAL/80 Structured Macro Assembled Language — 
Package ol powerlul general purpose text macro proc- 
essor and SMAL structured language compiler. SMAL is 
an assembler language wilh IF- THEN-ELSE. LOOP- 
REPEAT-WHILE. DO-END. BEGIN-END constructs 
S75/$15 

□ SELECTOR I1I-C2 — Data Base Processor to creale 
■« and maintain multi Key data bases Prints lormatted. 

sorted reports with numerical summaries or mailing 
labels. Comes with sample applications, including Sales 
Activity, Inventory. Payables, Receivables, Check Regis- 
ter, and Client/Palienl Appointments, oic. Requires 
CBASIC-2 Version 2.Supplied in source code S293/$20 

□ CPM/374X — Has lull range ol functions lo creale or 
re-name an IBM 3741 volume, display directory infor- 
mation and edit the data set contenls Provides full lile 
Iransfer facilities between 3741 volume dala sets and 
CP.'M files $195'$10 

D BASIC UTILITY DISK — Consists of: (1) CRUNCH- 
fwi ]4 _ Compacting utility to reduce the size and increase 
Ihe speed ol programs in Microsoft Basic and TRS-80 
Basic. (2) DPFUN - Double precision subroutines for 
computing nineteen transcendental lunclions including 
square root, natural log, log base 10. sin. arc sin. hyper- 
bolic sm. hyperbolic arc sin, etc. Furnished in source on 

diskette and documentation $50 $35 

P THE STRING BIT — Fortran character string han- 
,Ul dlmg. Routines lo find, fill, pack, move, separate, con- 
catenate and compare character strings This package 
completely eliminates the problems ' a-ssockilod wi'ih 
character string handling in FORTRAN Supplied with 

source $4S/$15 

LJ BSTAM — Utility lo hnkfQpe computer to anolner also 
" oquipped y^rfH BSWJX/lkiws lile transfers at 'ull data 
speed (no cpwei&riiTto hex^yJilh CRC block control 
check for ve>y reiia^^e1 : ]rJ^eciion And automatic re- 
try. We use it'-lfs^reltL-fiJS wildcard expansions to 
send * COM. ritr/9M0 baup >*)lVwire. 300 baud with 
phone connection. Both ^irWb'd'ono Standard and M 
versions can talk lo one'anolher. Compadble TRSDOS 
version also available $1 so ss 

•••••• 

SUNDRIES 

&NOTIONS 

□ HEAD CLEANING DISKETTE -- Clear,:-, me drive 
read/write head in 3G uacends On-l-.'.:!i>- , ilr. or us loose 
11. nit- part iclf.-r I iiijier prmli. and other foreicin panicles 
th.il in. QUI li.n.liu Ihii performance otthi: drive head 
Lasts at leant 3 month:, with daily use Specify 5 " or 8" 

S20. n»,, S45. for 3 

D Flippy Disk Kit — Template and instructions lo modify 
single sided Sid" diskettes lor use of second side in sin- 
gle sided drives St 2.50 

□ FLOPPY SAVER Protection tor center holes of 5'.*" 
Iloppy disks Only 1 needed per diskette Kil contains 
centering post, pressure tool, lough 7-mil mylar remlorc- 
ing nngs. Installation lools and rings lor 25 diskettes 

$1 4.95 

Re-0'ders ol rings only . . $7.95 

□ PASCAL USER MANUAL AND REPORT- By 

Jensen and Wulfi.Tfii? standarp lextbookon tne lad 
guaqe Recommer-rt.'d for jse by Pascal'Z. Pascal'M 
and Pascal^MT users , $8 

D THE C PROGRAMMING LANGUAGE - By 
Kernighan and Rilchie.. The" Standard textbook on the 
language. Recommended lor use by BDS C, tiny C, and 



hilesmiths C u 



$12 



****** 





eboat Associates 

tfARE 



Orders musl specily disk 
syslems and lotmafs: 
e.g. North Star single, 
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IBM single or 2D 256, 
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5Vj" soil sector(Micro 
iCOM'SD 5yslems 
Dynabyte). elc. 
Prices FOB. New York 
Shipping, handling and 
COD. charges exlra 

Manual cost applicable 
againsl price ol 
subsequent sollware 
purchase. 
The sale ol eacf 
propnelaiy software 
package conveys a 
license for use on one 
system only. 



Lifeboat Associates, 2248 Broadway. n.y„ n.y. 10024 
(212) 580-0082 Telex: 220501 j^/M^^/j 



;; 



KTHOME 
BlTSET 

Clearbit 

DO IT NOW 

Enter 
Factor ■ 
Go step 
Half step 
Initialize 
Jog 

Leftright 
Number 
Onestep 
Position 
Quit 
Bate 
Slope 
loop TIL 
Until 

+ CCW) - (CCW) 



Tell it 

and forget it... 

... the new CY500 stored 
program stepper motor 
controller runs its own program, 
freeing your host computer 
for other jobs. 

No more one-pulse, one-step operation 
requiring your host computer to tie 
itself down to a stepper motor. Now 
Cybernetic Micro Systems brings you 
a function-oriented stored program 
stepper motor controller that allows the 
user, or host computer, to program 
it and forget it . . . 

The CY500 executes 22 hi-level 
instructions, either in command mode 
or as a sequence of internally-stored 
commands, using single byte code such 
as 'F for position, 'R' for rate, and 'S' 
for slope. Parameter values can be 
expressed in ASCII-decimal for 
keyboard programming or binary code 
from the host computer. Parallel or 
serial communication. 

The stored program capability allows 
the use of 'DO-WHILE' program looping 
and 'WAIT-UNTIL operation. Ten 
different operational modes allow 
absolute or relative positioning, full- 
or half-step operation, hardware or 
software control of direction, start/stop, 
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Numerous input and output control 
lines allow synchronizing the CY500 
with external events or devices and 
allow each step to be triggered. 
Stepping at rates up to 3500 steps/sec, 
the CY500 also provides ramp-up, slew, 
and ramp-down operation, all under 
software control. Two interrupt lines 
request the host's attention if needed. 

This +5 volt N-MOS TTL-compatible 
controller is available from stock, today, 
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(415)949-0666 

(Use your MASTER CHARGE or VISA 
charge card) 




Listing 1: Gasuse program for determining mileage, gas efficiency, and keeping track of 
gas expenses. 



10 
40 
50 
110 
1010 
1020 
1030 
1032 
1035 
1037 
1039 
1040 
1050 
1060 
1070 
1075 
1080 
1081 
1082 
1083 
1084 
1100 
1110 
1115 
1120 
1124 
1126 
1130 
1140 
1160 
1170 
1190 
1195 
1200 
1210 
1220 
1230 
1245 
1248 
1250 
1252 
1255 
1260 
1290 
1900 
2000 
2010 
2020 
2030 
2050 
2080 
2090 
2100 
2110 
2120 
2130 
2150 
2180 
2190 
8100 
8110 
8111 
8115 
8120 
8150 
8160 
8170 
8180 
8190 
9400 
9404 
9406 



REM PROGRAM GAS TO FIGURE MILEAGE 

REM SCRATCH F "GASUSE" 

REM SAVE DC F ("GASUSE") "GASUSE" 

U$ = HEX(OC) 

PRINT " I COMPUTE AND DISPLAY GAS MILEAGE" 

ENTER ZERO FOR UNKNOWN FIGURES, I WILL TRY" 

ENTER ZERO FOR MILES TO STOP" 



ENTER 1. FOR SCREEN DISPLAY" 
2. FOR PRINTER OUTPUT" 



GALLONS"; 
DOLLARS' 



PRINT ' 

PRINT ' 

PRINT 

PRINT' 

PRINT ' 

INPUT P9 

PRINT 

PRINT "STARTING MILES"; 

INPUT MO 

M7=MO 

IF P9 = 2 THEN 8100 

PRINTUSING 1081 

% COST DISTANCE TOTAL AVE TOTAL TOTAL 

PRINTUSING 1083 

% MILES GAL MILEAGE MILES MILEAGE COST GAL 

PRINT 

PRINT U$; "NEXT MILES"; 

INPUT M1 

IF M1 =0THEN 1900 

IF M1>M7 THEN 1130 

PRINT U$; " THIS MILES LESS THAN LAST, OR SAME" 

GOTO 1100 

PRINT U$;" 

INPUT G1 

PRINT U1;" 

INPUT D1 

IFG1 =0THEN 2000 

IF D1 =0THEN 2100 

REM 

M8 = M1-M0 

D8 = D8 + D1 

G8 = G8 + G1 

IF P9 = 2 THEN 8150 

PRINT U$; 

PRINTUSING 1252,M1,D1,G1,M1-M7,(M1-M7)/G1,M1-M0;M8/G8,D8,G8 

%###### $§#.#§ ##.# ### ##.# ##### ##.# »##.## ###.# 

PRINT 

M7 = M1 

GOTO 1100 

STOP 

PRINT U$; " GALLONS ENTERED AS ZERO, ENTER CENTS/GALLON"; 

INPUT C1 

IF D1=0THEN 2080 

G1 =D1/(C1/100) 

GOTO 1200 

PRINT U$; " DOLLARS ALSO ZERO, NO CALCULATION POSSIBLE"; 

GOTO 1100 

PRINT U$; 

INPUT C1 

D1 = G1*(C1/100) 

IF D1 =0 THEN 2180 

GOTO 1200 

PRINT U$;" CALCULATION RESULT IS ZERO; REENTER " 

GOTO 1 1 00 

SELECT PRINT 215(80) 

PRINTUSING 1081 

PRINTUSING 1083 

SELECT PRINT 005(64) 

GOTO 1084 

SELECT PRINT 215(84) 

PRINTUSING 1252,M1,D1,G1,M1-M7, (M1-M7)/G1,M1-M0;M8/G8,D8,G8 

SELECT PRINT 005(64) 

PRINT U$;TAB(64) 

GOTO 1 260 

DEFFN'O "LISTS" 

DEFFN'1 ",9999" 

DEFFN'2 "000,9999" 



DOLLARS ENTERED AS ZERO, ENTER CENTS/GALLON' 













TOTAL 


AVE 


TOTAL 


TOTAL 


LES 


COST 


GAL 


DISTANCE 


MILEAGE 


MILES 


MILEAGE 


COST 


GAL 


1202 


$4.19 


7.5 


201 


26.8 


201 


26.8 


$4.19 


7.5 


1453 


$5.75 


10.1 


251 


24.8 


452 


25.6 


$9.94 


17.6 


1604 


$2.59 


5.0 


151 


30.2 


603 


26.6 


$12.53 


22.6 


1715 


$3.45 


6.2 


111 


17.9 


714 


24.7 


$15.98 


28.8 


1995 


$3.95 


6.9 


280 


40.1 


994 


27.7 


$19.93 


35.7 



Table 1: Sample output from listing 1. To determine accurate gas usage take an average 
over several results. 



Circle 52 on inquiry card. 




Stanley's office staff says Stanley always stays 
one step ahead. So no one was surprised when he 
showed up with Microsoft's COBOL-80 for the 
office computer. That's when things started 
happening. 

As Stanley explains, "Suddenly, the whole 
business operation is more efficient. I use it for 
everything: inventory, payroll, record keeping, 
customer and employee files. Since COBOL is the 
standard language for business and commercial 
applications, more programs are written in COBOL 
than any other language. Believe me, nothing 
beats it in terms of powerful use of disk files, 
data manipulation facilities and interactive ter- 
minal communications!' 

Stanley added loudly, "And that's versatility and 
efficiency I'd like to see more of around here. 

"My COBOL-80 package from Microsoft 
includes the MACRO-80 assembler, LINK-80 
linking loader and LIB-80 relocatable library 
manager. I can even call FORTRAN, BASIC, 
assembler and COBOL modules from a COBOL- 
80 program. It's perfect— a total software develop- 
ment package',' exclaimed Stanley. 

Microsoft's COBOL-80 is an ANSI-74 standard 
COBOL that supports such advanced data 
manipulation verbs as COMPUTE, INSPECT, 
STRING, UNSTRING AND SEARCH: three- 
dimensional arrays; full COPY facility; and com- 



plete screen handling capability. The optional 
packed decimal format saves on mass storage by 
as much as 40%. And as Stanley puts it, "With 
my floppy disk system, that's a big plus!' 

Stanley can't say enough about his new addition 
to the office. "COBOL-80 supports indexed and 
relative files, including DYNAMIC access, FILE 
STATUS, START, READ NEXT, DELETE 
and REWRITE. Best of all, interactive ACCEPT/ 
DISPLAY gives the most powerful screen handling 
capability possible. 

"Frankly!' says Stanley, "Microsoft COBOL- 
80's performance is so superior it's set a whole 
new standard of efficiency for my staff. My new 
motto? 'Shape up or ship out! Thanks Microsoft, 
my office will never be the same!' 

The COBOL-80 package for the CP/M or 
ISIS-II operating system with documentation is 
$750. Documentation may be purchased sepa- 
rately for $20.„Dealer purchases and OEM 
license agreements available on request. 





urn 



10800 N.E. Eighth Suite 819 
Bellevue, Washington 98004 
206/455-8080 Telex 328945 

We set the standard. 



FI 




Circle 53 on inquiry card. 



Programming Ouickies 



String Comparator 
for Horizon 



Richard W Lindberg, 9302 Mayrene Dr, 
Garden Grove CA 92641 

As a recent purchaser of a personal computer, and an 
even more recent subscriber to BYTE, I look for program- 
ming articles to help expand the horizon of my Horizon. I 
scanned the September 1979 issue as soon as it arrived, 
and was intrigued by the article "A Similarity Com- 
parator for Strings," by T C O'Haver on page 58. Realiz- 
ing changes would be necessary, I immediately set out to 
translate it to run in North Star BASIC. 

The first change required was the replacement of the 
string operator MID$(A$,I,1) with A$(I,I) in statements 
130, 140, 230, and 240. (Note that North Star also allows 



Listing Is Similarity comparator program in North Star BASIC, 
adapted from the program by T C O'Haver. 



8 


DIM A$(64),B$(64),Z$(64),A1$(64),B1$(64) 


10 


T = 


20 


P = 3 


30 


F'FIRST WORD", 


40 


INPUT Al$ 


50 


A = LEN(A1$) 


55 


A$(1,A) = A1$ 


60 


("SECOND WORD", 


70 


INPUT Bl$ 


75 


IF A1$ = B1$ THEN ! "EXACT MATCH" 


80 


B = LEN(B1$) 


85 


B$(1,B) = B1$ 


90 


IFA>BTHENB = A 


100 


FOR M = 1 TO B 


110 


C = 


120 


FOR 1=1 TOM 


130 


K$ = A$(B-M + I,B-M + I) 


140 


L$ = B$(I,I) 


150 


IFK$ = L$THENC = C + 1 


160 


NEXT I 


170 


C = CtP 


180 


T = T + C 


190 


NEXTM 


200 


FOR M = B + 1 TO 2*B-1 


210 


C = 


220 


FOR 1=1 TO 2*B-M 


230 


K$ = A$(I,I) 


240 


L$ = B$(M-B + I,M-B + I) 


250 


IF K$ = L$THENC = C+1 


260 


NEXT I 


270 


C = C1P 


280 


T = T + C 


290 


NEXTM 


300 


S=100*T/BtP 


310 


!S,"%" 


320 


T = 


325 


B$ = Z$ 


330 


GOTO 70 


340 


END 



the implied LET and the use of ! for PRINT.) The next 
change was the addition of a DIMension statement to 
allow strings greater than 10 characters in length. Then 
when trying to compare two strings of different length, 
the computer threw me out! This necessitated having 
enough blanks in the shorter string to match the length of 
the longer one. To accomplish this, strings A$ and B$ 
were set to 64 blanks by the dimension statement, and 
temporary strings Al$ and Bl$ were used to read in the 
input string data and compute the lengths A and B. Al$ 
was then placed in the first A characters of A$, and Bl$ 
in the first B characters of B$, leaving the remaining 
characters blank. Blank string Z$ is used to reset B$ to 
blanks before testing a new string, otherwise there would 
be unwanted characters left in B$ if the previous string 
were longer than the new string. This was noticed when I 
followed O'Haver's test sequence, and found that POO 
gave a 100% match with POOL, because the previous 
test string was COOL and the L was still there. So with 
the addition of line 325, 1 knocked the L out of it and had 
the program running. The address strings took many 
seconds to run. 

Listing 1 gives the program as adapted to North Star 
BASIC Version 5.0, and listing 2 shows a sample run for 
comparison with the published run. Note that the agree- 
ment is quite good except for POOL ROOM, MAIL 
ROOM, and the long address strings. These differences 
are possibly due to the addition of the trailing blanks to 
fill the shorter string. A speedier version would be even 
more useful, and I am looking forward to the assembly 
language version — who would like to write it? 



Listing 2: Two sample executions of the program in listing 1. 

RUN 

FIRST WORD ?POOL 
SECOND WORD ?POOL 
EXACT MATCH 

103.125% 
?POOR 

45.3125% 
?COOL 

45.3125% 
?POO 

45.3125% 
?POLO 

28.125% 
?LOOP 

18.75% 
?PAIL 

12.5% 
?POOL ROOM 

20.164609% 
?MAIL ROOM 

3.0178326% 
?PO/OL 

14.4% 

?oooo 

40.625% 

RUN 

FIRST WORD ?T.C. O'HAVER 710 HILLSBORO DR. SILVER 

SPRING MD. 

SECOND WORD ?TOM O'HAVER 710 HILLSBORO DR. SILVER 

SPRING MD. 

77.241074% 
?R.D. O'HAVER 710 HILLSBOROUGH RD. SILVER SPRINGS FL. 

14.492063% ■ 



86 February 1980 © BYTE Publications Inc 




APPLE OWNERS - 

EXPAND YOUR SYSTEM 

WITH 8" FLOPPY DISK 

FROM WIZARD* 

WIZARD 

Many software programs are restricted by the 1 1 6 K available on the 5" disk 
drives now on the market. Some business programs require 1 2 or more disk- 
ettes, which can be both confusing and error inducing. 

WIZARD offers four solutions: 

'•WIZRRD\ + 1": single 8" drive system; 256 K $1695. 

'WIZARD 2 + 2" : two 8" drive system; 516 K $2495. 

"WIZARD PLUS" : two 8" drives, double sided; over 1 megabyte $3150. 

"WIZARD 1 0" : 1 megabyte Winchester drive, formatted as one file. $4795. 

All systems are ready to run, fully assembled and tested, and include: 

SHUGART full size 8" floppy disk drive(s). 

Controller Card for your Apple (48K RAM required) 

All interface software, cables, connectors, cabinet and power supply. 

ONE YEAR parts and labor warranty from defects in material and workmanship. 

WATCH FOR NEW WIZARD PRODUCTS FROM D&T ELECTRONICS: 
we are currently developing other hardware and business software. 



ALL SYSTEMS AVAILABLE NOW (stock to two weeks). 
SEE YOUR LOCAL APPLE DEALER, OR CONTACT THESE WIZARD DISTRIBUTORS: 

MAR-COMP COMPUTER DISTRIBUTORS, INC. 

175 East Edgewood Drive PO BOX 9194 

McMurray, PA 15317 Austin, TX 78766 

(412)531-5445 (512)345-9729 

DEALER INQUIRIES INVITED 



SOFTWARE: We have software available to run on these expanded capacity systems; please 
send for our list. 

If you are a software writer and have programs currently on 5" that would 
benefit from the expanded capacity of our 8" systems, we would like to hear 
from you. 

WIZARD is a registered trademark of D&T Electronics, Inc. 
Apple is a registered trademark of Apple Computer, Inc. 



Circle 54 On inquiry card. BYTE February 1980 87 



Blubs and Newsletters 



Sorcerer User's Group 
in Ann Arbor Ml 

The Sorcerer User's Group 
and their newsletter, The 
Sorcerer's Apprentice, are 
based in Ann Arbor MI. 
The group meets once a 
month at the Newman Com- 
puter Exchange and the 
newsletter is printed every 
month and a half. The 
group's object is to spread 
Sorcerer-related information 
to all owners and to get as 
much out of the machine as 
possible. Contact Dave 
Bristor, 1530 Washtenaw, 
Ann Arbor MI 48104. 



Computer Group for 
Medicine and Science 

Microcomputers in 
Medicine and the Sciences 



Association is an organiza- 
tion devoted to aiding 
members of the medical and 
scientific communities gain 
working knowledge of com- 
puters and their uses in 
research and practical ap- 
plications. Meetings are ac- 
credited seminars covering 
languages and applications 
of microcomputers. They 
meet in the Chemistry 
Building, Rm 105, Universi- 
ty of South Florida, Tampa 
FL, on the fourth Thursday 
of the month at 7:30 PM. 
Their newsletter is called 
MI MSA News. 



Software World 

Called the Software 
World, this quarterly 
publication from England 
contains programs, book 




computer mart 
of n»w j»r s»y 




[Computer Mart of New Jersey 

501 Route 27 

Iselln, N.J. 06830 

(201)283-0600 

HOURS, 

Open ot 10 am, 

Tuesday through Saturday 



the 

microcomputer 

people® 

THE VITAL 
INGREDIENT: 

EXPERTISE 



Before you buy your new 
microcomputer, chances are 
you hove a lot of questions. 
Important questions that 
could mean the difference 
between a working system 
and a wasted system. The 
vital Ingredient Is expertise. 
The microcomputer people at 
Computer Mart are expert at 
answering your questions 
and helping you put together 
the best system for your 
application. Whether It's for 
business, the home, or the 
laboratoryi come see the 
experts at Computer Mart 
of New Jersey. We have the 
vital Ingredient. 



reviews, new products, and 
computer related business 
items. The subscription rate 
in the US is $64 a year. The 
newsletter is one of a series 
of three software related 
publications from A P 
Publications Ltd, 322 St 
John St, London EC1V 4QH 
ENGLAND. 



Compucolor User's 
Group 

The Canadian Com- 
pucolor User's Group meets 
on the second Wednesday of 
every month and invites 
users as well as interested 
onlookers to join and utilize 
the program library. For 
more information, contact 
House of Computers Inc, 
368 Eglinton Ave W, Toron- 
to, Ontario M5N 1A2 
CANADA. 



Club 1802 
Newsletter 

Club 1802 is a newsletter 
published for users of 
microcomputers which are 
based upon the 1802 pro- 
cessor. Programs, book and 
program reviews, want ads, 
items for sale and letters on 
related subjects are included. 
The newsletter is published 
twelve times a year and cur- 
rent rates are scheduled to 
be about $10 a year. For 
more information, contact 
Club 1802, POB 985, 
Dickinson TX 77539. 



Apple Dayton 

This Apple II users group 
alternates their meeting 
dates between the second 
Wednesday of odd 
numbered months and the 
second Thursday of even 
numbered months to allow 
different people to attend at 
least bi-monthly. Meetings 
are held at Computer Solu- 
tions, 1932 Brown St, 



Dayton OH, at 7:30 PM. 
For more information, con- 
tact Apple Dayton, Robert 
W Rennard, 2281 Cobble 
Stone Ct, Dayton OH 
45431. 



Sorcerer User's 
Group Newsletter 

The Exidy Monitor is a 
monthly newsletter intended 
for users of Sorcerer 
microcomputers. The 
newsletter contains pro- 
grams and other technical 
articles plus a software 
library buyer's guide for 
members and nonmembers. 
For information, write to 
The Exidy Monitor, c/o 
Computer Mart of 
Massachusetts, 1395 Main 
St, Waltham MA 02154. 



Computer Club in 
Central Nebraska 

Compusers is a new club 
for anyone interested in 
computing, particularly 
owners or prospective 
owners of microcomputers 
of any make. Meetings are 
held on the third Monday of 
each month at 8 PM. Dues, 
by-laws, and permanent of- 
ficers are not yet establish- 
ed. For more information, 
contact Rocky Friend, POB 
2064, Hastings NE 68901. 
Their monthly newsletter is 
also available from the same 
address. 



West German 

Microcomputer Club for 

Radio Amateurs 

The DAFG/GART Ger- 
man Amateur Radio 
Teleprinter Group has 1300 
members who use SDK-85, 
KIM-1, PET 2001, TRS-80, 
Apple II, and other 
microcomputers for amateur 
radio operation in RTTY, 
FAX, SSTV, or CW. The 
membership fee is DM 35.00 
annually. The newsletter, 
RTTY, is published six times 
a year. For more informa- 
tion, contact Manfred N 
May, Herrenstr.56, D 5014 
Kerpen-Sndf. Or contact R F 
Matthaei, Beisserstr.45, D 
2000 Hamburg-63, uC- 
Referat, WEST GERMANY. 



88 February 1980 © BYTE Publications Inc 



Circle 55 on inquiry card. 



L 




11 



SO RELIABLE WE GIVE YOU 



f 




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350 351 352 353 354 

345 346 347 348 349 

340 341 342 343 344 



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225 226 227 228 229 




TOTAL PEACE OF MIND. 

We are business people, just like you. We wouldn't stick our 
neck out unless we were certain we could back our claims and 
promises to the last letter. We wouldn't offer a legally binding 
long-term warranty on our Microtek MT-80, unless we were 
positive of its solid reliability. 

We are sure that our versatile, alphanumeric line printer will 
provide you consistent, dependable performance. This is why 
we give you, not the usual 90-days in fine print, but an incredible 
365-days warranty. We stand behind every product we make. 

LOADED WITH INNOVATIONS 

• 40, 80 or 1 20 columns (software selectable) 

• Non-thermal paper, pin feed 

• 125 CPS, 70 lines per minute 

• 9 x 7 dot matrix 

• Vertical format unit 

• 96-character ASCII (upper and lower case) 

• Adjustable forms width to 9 Vs> " 

• Parallel, serial (RS-232C), and IEEE-488 
interfaces available 




OUR UNIT PRICE 

$750. Parallel 

$835. Serial (RS-232C) 

$895. IEEE-488 



For more information contact: 

MICROTEK, Inc. 
7844 Convoy Court 
San Diego, CA 921 1 1 
Tel. (714)278-0633 

Circle 56 on Inquiry card. 



Free Newsletter on 

Process Instrumentation 

Systems 

A newsletter series entitled 
ControLoops covers the 
fundamentals of industrial 
process instrumentation and 
control systems. Theory and 
implementation on unit con- 
trol systems including 
cascade control, auctioneer- 
ing, and feedforward con- 
trol, plus application 
diagrams are featured in the 
series. For a free subscrip- 
tion to ControLoops, con- 
tact E Ross Forman, 
Manager — Instrumentation 
Engineering Group, Day and 
Zimmermann Inc, 1818 
Market St, Philadelphia PA 
19103. 



PAX (Program 

Analysis Exchange) 

Succeeds 52-Notes in 

a New Format 

PAX is a publication 
devoted to the analysis and 
evaluation of widely used 
personal computing softwa - 



currently on the public 
market for which good sup- 
porting documentation is 
not known to exist. Back 
issues of PAX and 52-Notes 
are available for $1 each. 
Write to Richard C Vander- 
burgh, 9459 Taylorsville Rd, 
Dayton OH 45424, to obtain 
information on contributing 
articles. 



Ontario Society for 

Microcomputers in 

Education 

A group of seventy 
educators have started the 
Ontario Society of 
Microcomputers in Educa- 
tion in order to coordinate 
individual efforts and pro- 
vide a clearinghouse for the 
exchange of information on 
equipment, curricular 
materials, and teaching 
methods. The group's aims 
are to promote the use of 
microcomputers in all 
aspects of education, share 
knowledge of hardware and 
software, develop strategies 
for demonstrating the uses 



of microcomputers in the 
classroom, to assist in the 
development of software to 
meet specific curricular 
needs, and more. For more 
information, contact N 
Solntseff, Unit for Computer 
Science, McMaster Univer- 
sity, Hamilton, Ontario, 
L8S 4K1 CANADA. 



International Computer 
Club 

The International Society 
of Personal Computerists 
was organized to promote 
and advance personal com- 
puting on a world-wide 
basis. The society's services 
include free software, free 
consultation, custom pro- 
gramming, conversions from 
one BASIC system to 
another, and group dis- 
counts on software and 
hardware purchases. Tid- 
Bits, the newsletter, is of 
broad general interest to 
computer users and hob- 
byists. The society publishes 
several other newsletters 



tailored to Apple users, 
Heath users, TRS-80 users, 
beginners, and nonusers. 
Membership is $15. Contact 
International Society of Per- 
sonal Computerists, 4554 
Cristy Way, Castro Valley 
CA 94546. 



Southern New 
Hampshire Apple Group 

The Southern New Hamp- 
shire Apple Core meets once 
a month. The group is 
dedicated to Apple users, 
and they currently have 
plans to give public 
demonstrations of com- 
puters. Their newsletter is 
entitled SNAC Facts and it 
contains information con- 
cerning the meetings, items 
of general interest, and short 
programs. The members are 
building a disk library and 
are interested in hearing 
from other Apple users. 
Dues are $6 per year. For 
more information, contact 
SNAC, Computerland of 
Nashua, 419 Amherst St, 
Nashua NH 03060. ■ 



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ELECTRONIC CONTROL TECHNOLOGY (zod gsg soso 



90 February 1980 © BYTE Publications Inc 



Circle 57 on inquiry card. 



TEX and 

by Donald E 



l|> and MKIAKOM 



METAFONT, New Directions in Typesetting 

Knuth 

TEX and METAFONT,New Directions in Typesetting describes two systems that are going to change 
the typesetting/publications world. TEX is a system for typesetting technical text currently being im- 
plemented in PASCAL. It is in the public domain and is available to all who are involved in computerized 
typesetting. METAFONT, a system for design of alphabets suited to implementation on raster-based 
devices, permits a designer to give a completely precise definition to an infinite variety of typefaces. TEX and 
METAFONT are unique and powerful achievements whose concepts will be useful to: authors and 
publishers; programmers and system designers in typesetting, graphics, and office automation; typeface 
designers and commercial artists; compositors; university computing centers; and manufacturers of typeset- 
ting equipment. Foreword by Gordon Bell. A co-publication of Digital Press and the American Mathematical 
Society. 1979, 360 pp., ISBN 0-932376-02-9, paperback, $12*. 



Data Processing Technology and Economics, Second Edition 

by Montgomery Phister, Jr. 



Data 

Processing 

Technology 

and Economics 



Data Processing Technology and Economics, Second Edition, is a comprehensive study of the data 
processing industry from its inception through 1978-79. It provides quantitative data and insightful nar- 
rative on four topic areas: the marketplace, products, applications, and costs. Coverage includes operating 
costs (to the user) and development, manufacturing, marketing, and maintenance costs (to the supplier). 
Other topics include hardware and software reliability, computer (and peripheral) population, system perfor- 
mance with multiprogramming, software performance and usage, I/O technologies and costs, computer use 
by industry and government, principal applications, human performance factors, and the important com- 
puters. Data Processing Technology and Economics is for users, applications programmers and 
systems analysts, system programmers, hardware designers, and managers. A co-publication of Digital 
Press and the Santa Monica Publishing Company. 1979; 736 pp.; hardbound (ISBN 0-932376-03-7), 
$29.95*; paperback (ISBN 0-932376-02-9), $24.95*. 



Computer Engineering: A DEC View of Hardware Systems Design 

by C. Gordon Bell, J. Craig Mudge, and John E. McNamara 




Computer Engineering: A DEC View of Hardware Systems Design is the story of hardware systems 
design practiced at Digital Equipment Corporation from 1957-77. It provides a set of case studies of classic 
design principles and techniques practiced under the real-world constraints of marketplace economics and 
continually evolving technology; an overview of the computer industry— insight into the complexities of its 
interrelated forces and an historical perspective; and a description of the development of families of 
machines. Computer Engineering is for people who want to understand the evolution of hardware 
systems design: hardware systems designers, university students (used in computer architecture courses at 
Caltech and UC/Berkeley); management of companies planning systems or planning to buy systems; soft- 
ware engineers; users. 1978, 585 pp., ISBN 0-932376-00-2, hardbound, $19.95*. 



Technical Aspects of Data Communication 

by John E. McNamara 




QDIDDSD 



Technical Aspects of Data Communication provides a practical approach to the nuts-and-bolts prob- 
lems and solutions in configuring communications systems. It describes common pitfalls in systems design 
and ways to avoid them, while also serving as a useful reference tool. Technical Aspects of Data Com- 
munication is intended to fit between books that treat data communication solely on a system level and 
hardware manuals that specify in detail the function of each bit in each register. The book features: com- 
parison of protocols (DDCMP, BISYNC, SDLC), extensive explanation of interface standards (CCITT/V.44, 
RS232C, RS422, RS423) comprehensive appendices (how far — how fast?, modem options, codes (Baudot, 
ASCII, and others), UART, format and speed table for asynchronous communication, channel 
conditioning). Other topics covered are the 20-milliampere loop, telephone switching systems, error detec- 
tion, and digital transmission and packet switching networks. 1977, 382 pp., ISBN 0-932376-01-0, hard- 
bound, $19.95*. 

Digital Press, Educational Services 

Digital Equipment Corporation 

12-A Esquire Rd., Billerica, MA 01862 



ORDERING INFORMATION 

'Prices are U.S. only. (Contact your nearest office of Digital Equipment Corporation, Educational Services for prices outside 
U.S.) Ten percent discount for two or more copies. Shipping and handling charges will be added to all orders not prepaid. 

Please specify number of copies: 

TEX and METAFONT, New Directions in Typesetting 

Data Processing Technology and Economics, Second Edition 

□ hardbound □ paperback 

Computer Engineering: A DEC View of Hardware Systems Design 

Technical Aspects of Data Communication 



□ Check enclosed. □ Please invoice me. (Specify billing address if different 

from shipping address.) 
Remit to: Dept.DPC, Digital Press, at the address above. 

Circle 58 on inquiry card. 



BYTE February 1980 91 



Implementing Dynamic Data 
Structures with BASIC Files 



Ted Carter 

902 Pinecrest 

Richardson TX 75080 



In many computer applications 
where a large amount of information 
is to be stored, the need arises to sort, 
insert, and delete items efficiently 
using random-access tape or disk- 
based files. A common method of 
implementing a mailing list, for ex- 
ample, is to add new names to the end 
of the current file and to delete names 
by putting a blank field in place of the 
names to be deleted. This minimizes 
the number of time-consuming reads 
and writes to the file. 

However, when this mailing list 
has to be printed in zip-code order, 
for example, the task becomes 
extremely slow as the number of 
names increases. This is because the 
number of file accesses increases ex- 
ponentially with the number of items 
to be sorted. One possible solution is 
to actually sort the file so that it is 
always in order. This is impractical 
because it necessitates the same sort 
operation as before, plus a complete 
rewrite of the file. 

With close examination of the pro- 
blem, you might decide that the file 
should always be kept in order by 
inserting a new name in its proper 
place. This is a good idea, but 
requires that you must move, on the 



About the Author 

Ted Carter is employed at the Texas In- 
struments Corporate Engineering Center. In 
1978, he founded Software Industries, a cus- 
tom software house. His interests include com- 
puter speech synthesis and computer automa- 
tion. 



average, N/2 names (for a file of N 
names) to make room for the new 
names. Again, with large files, this 
may take an inordinately large 
amount of time. 

In order to solve these problems 
successfully and efficiently, you need 
a data structure that will permit an 
insertion and deletion of components 
without having to worry about where 
new components fit or what happens 
to the empty space left by deletion. 
The tool needed to create such a 
structure is called a pointer. This is 
simply a number that points to the 
location of a desired piece of data. 
Using disk files, for example, a 
pointer to a piece of data is its actual 
record number on the disk file. This 
takes advantage of the random access 
capabilities of a disk file so as to 
directly locate and read the data using 
the pointer value. 

Using pointers, a linked list, the 
simplest type of dynamic data struc- 
ture, can be built. In order to build 
the linked list, every data record must 



be accompanied with a pointer to the 
next element in the linked list. 
Therefore, space must be reserved in 
the file for a pointer value within each 
data record. 

A linked list is shown pictorially in 
figure 1. In a disk file, for example, 
you could store the base pointer value 
in the first record of the file. 
However, you need some way of 
knowing that the last data item Z 
does not point to anything. This can 
be accomplished by storing some 
special number not in the range of 
possible pointer values, such as zero, 
as the pointer value associated with 
the last data item. An important thing 
to realize is that records X, Y, and Z 
can physically be in any order on the 
disk. However, they are linked in 
order and can be retrieved in order 
with absolutely no comparing or sort- 
ing. 

Record insertion is also relatively 
simple. The ordered list is scanned 
until the element to be added is 
greater than or equal to the current 



Figure 1: Example of a linked list. In this picture, X, Y, and Z are records containing the 
information that is to be stored. The boxes on top represent a portion of memory con- 
nected with each record that contains the address of the next record in the list. These are 
called pointers. The first record in the file, called the base record, points to the first data 
record in the file but does not contain data itself. This is because the base record also 
contains a pointer (not shown) to the first available space for new records. 



92 February 1980 © BYTE Publications lnc 



THE 

INFLATION 



FIGHTE 




You can't buy more 
capability for less ... But 
you can buy less for more 




Circle 59 on inquiry card. 



MPI presents the perfect answer to your inflation-riddled printer budget. THE MODEL 88T DOT 
MATRIX PRINTER. The first in a series of new full-capability low-cost printers designed specifically 
for the general use computer market. The Model 88T is a fully featured printer with a dual 
tractor/pressure-roll paper feed system and a serial or parallel interface. The tractor paper 
feed system provides the precision required to handle multi copy fanfold forms, ranging in 
width from 1 inch to 9.5 inches. For those applications where paper costs are important, the 
pressure-roll feed can be used with 8.5 inch roll paper. A long-life ribbon cartridge gives crisp, 
clean print without messy ribbon changing. The microprocessor controlled interface has 80, 96 
or 132 column formating capability while printing upper and lower case characters bi- 
directionally at 100 characters per second. 

With all of these features, plus quality construction, continuous duty print head and attractive 
styling, the Model 88T would easily sell at the competition's "under $1000" (999. Q0 ) tag. But we 
are offering it for only $749; this should make you happy and several hundred dollars richer, 

Write for complete specifications and pricing information. 



MICRO PERIPHERALS, INC. 2099 WEST 2200 SOUTH / SALT LAKE CITY. UTAH 841 1 9 / (801 ) 973-6053 

BYTE February 1980 93 



TRS-80, Apple II 
and S 100 owners. 

Busy Box. 

It makes your 
com 



it never 
did before. 




MicroMint introduces a new wireless 
AC remote control interface for the 
Sears and BSR X-10 home control 
system. Use your present TRS-80 
Level II, Apple II or S-100 computer to 
provide complete home security through 
control of lights, appliances and motors 
with a few simple Basic commands. 
Buss compatible with virtually all 
microcomputers. Completely assembled 
— Just plug in and turn on! 

As featured in: 

"COMPUTERIZE A HOME" 

BYTE, January 1980 



BUSY 
BOX 




Assembled and tested. 

Busy Box $79.95 

Cable and connector for TRS-80 14.95 

Cable and adapter for Apple II 29.95 

Cable and adapter for S-100 34.95 

Power Supply (necessary for TRS-80) 9.95 

NY residents add 7% sales lax. 

To order call (516) 374-6793 

or write: The MicroMint Inc. 
917 Midway 
Woodmere, NY 11598 
Dealer inquiries invited. 

TRS-80 is trademark of Tandy Corp. 
Apple II is trademark of Appie Computer 




The number of file accesses 

increases exponentially 

with the number of items 

to be sorted, 
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiin 

element and less than the next ele- 
ment in the list. The new element is 
then inserted between these two 
elements. For example, assume that 
Y2 is to be inserted before Z and after 
Y, as in figure 2a. This is achieved by 
placing Y2 physically in the first free 
position on the file, making Y2 point 
to where Y pointed, and making Y 
point to Y2, as in figure 2b. 

The process of deleting an element 
is easier. Consider deleting Y2 from 
the list in figure 2b. By making Y 
point to where Y2 pointed before Y2 
was deleted, the result is the list in 
figure 2a. 

In some situations, an improve- 
ment on the linked-list data structure 
is the doubly linked ring, shown in 
figure 3. With this structure, you may 



BASE 



scan from either direction, often 
facilitating an insertion and deletion 
either before or after an element. For 
ease of explanation and understand- 
ing, a simple singly linked list as in 
figure 1 will be used in the examples 
given in this article. 

Implementing the Linked List 

When implementing a linked list 
using random-access files, some addi- 
tional problems must be solved. An 
element can be inserted in the linked 
list easily enough, but the computer 
must know where the first empty disk 
file 'is located. Secondly, when 
deleting an element, the disk file loca- 
tion of the deleted record should be 
recovered for later use. 

These problems could be solved by 
marking the record to be deleted and 
later searching for the first empty or 
marked record when adding a new 
element. A much better solution is to 
create a linked list of free records. 
When adding a new element, a record 
is taken out of the linked list of free 
records and inserted in the ordered 



2a 



X 



BASE 



2b 

































Y2 
























• 














X 


Y 




Z 



Figure 2: The process of insertion in a linked list. Figure 2a shows a new record, Y2 (pro- 
bably physically located after nodes X, Y, and Z), before it is linked into its proper place 
in the list. To link it into the list, as in figure 2b, only the pointers in Y and Y2 must be 
changed. 



BASE 



Figure 3: Example of a doubly linked ring. In this kind of linked list, each record con- 
tains a pointer to the previous as well as to the next record in the list. This has certain 
advantages in some applications, although it creates more memory overhead in each 
node. Doubly linked lists are not discussed in this article. 



94 February 1980 © BYTE Publications Inc 




16K RAM 



Fully Static 
250 nsec. 



$295 



The model 24-103 "STANDARD" RAM was designed for the 
smaller system which does not require bank select. It has been in 
production since late 1978 and has earned an enviable record for 
reliability. Although it does not have some of the options of the 
commercial cards listed below, its manufacturing quality has not been 
cut in any way. The card has DIP switch addressing — any continuous 



16K on 4K boundaries. All inputs are buffered and it comes fully 
assembled and guaranteed for one year. Prices for the card with 250 
nsec. memory chips start at $295 and drop to $255 for quantities 5-9. 
You may deduct an additional $30 per board if you have a 2 Mhz. 
system and can get by with 450 nsec. chips. 



OTHER S-100 BUS STATIC RAMS 



16K PLUS 

This board has been sold primarily to dealers/system integrators 
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You may deduct $30 more for 450 nsec. chips. 



16K APEX 

The board is very similar to the PLUS card. It differs in that its bank 
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8/16 RAM 

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Listing 1: Program to create a linked list file. This program, written in CBASIC, creates 
a small file that contains forward pointers to the next available record. The first record, 
which is initialized to "2,3", points to the first data record in the file (record 2) and to the 
first empty (available) record in the file (record 3). The second record, initialized in line 
25, is a sentinel record that denotes the end of the file. It is always the last data record in 
the file and has a forward pointer of zero. 

jEFATE A FILE WITH A LINKED LIST OF FREE RECORDS 



REM 


REM 


REM 


REM- 


RFM- 


RR'M- 


E'EM- 


EEM- 


REM- 


REM- 


REM 


REM 


REM 


REM 



-There i.j i i i be 10 free records in the sample file, 

FILELENGTH=10 

-Create the file with a record length of 22- give 
-it the file number of one. 

CREATE "ClATA.FTL" REEL 22 AS 1 

- E u t b o ir.te r i n f o r t h e - d e i- e d 1 i n k e d da t a lis I 

-an d l i s t o f fret' records, 

PRINT #1 ! 2-3 
■-Rut ser.tenial with highest possible value at end 
-of l i nked list ..:. f data . 

PRINT 1*1. ! 0, "72ZZEZZ7 Z3J!7.r" 

-Create the linked list of free records lv, mdkina 
-each one Point to the n«vt record. 

FOR Z=4 TO FILELENGTH-l-2 : PRIN'i 1*1 : 7, < " " : NEX1 - 
-Make the last free list record po inter equal 
-zero to signify the end of the list. 

PRINT #1 ! 0, " " 

CLOSE 1 



Listing 2: Program to add a record to a linked list file. This program uses the forward 
pointers to chain through the linked list until the proper place for the new record is 
found. The only pointers that need to be changed are those on the record being added 
and the record immediately preceding it. 



EM 
EM 
EM 
EM 
EM- 



TEI 
UIH 



IS PROGRAM ADD: 
1LE KEEPING IT 



SOME ALF*HANUMER 
IN ALPHABET .1 CAL I 



DA 
WEfi 



PEM- 



REM--G 



IN 

-Le 
NE 



REM— 



PO I 



EM- 
EM— 



40 
45 



EM- 
EM- 



60 
65 

7 



til 
TR( 
PO 
IE 
In! 
-af ■ 
REM— 
REM— 

REM— 
REM— 



REM— 

REM— 
REM — 
REM— 



M "DATA. 
POi nter 

D # i . 1 : 
NEXTFREE 

data to 
I.JT"New d 
t J u s 1 1 f 
PATA*=LE 

p o i n t e r- 
NTER=BA 
r c h 1 o o p 
d the pp 
ILPOINTE 
MTER=NEX 
NEWDATA* 
ert ou 
er the e 
Get the 
t a k i n 9 a 
READ # 1 , 
If TRAIL 
be modi. < 
IF TRAIL 
PRINT #1 
PRINT #1 
Mom take 
PRINT #1 
No in make 
p o i n f e d 
p o i n t e d 
PRINT #1 
PRINT #1 
CLOSE 1 



ed 
REE 



#1 with record tenet 

EIL" REEL 22 AS 1 
S to start of I ml 
BASE POINTER- NExTP 
=0 THEM PR I NT "File is 

a d d . 
ata: "5NEWDATA* 
v data in a f i e I d o f b 
FT*(NEWDATA*+" 
5 to start of list. 
EPOINTER : ME XT POINTER 

m h i c h t r a v e r s e s t h e 1 
p e r p 1 a c e f o i n s e i ■ t t 
R=--pO INTER : PREVDATA*-- 
TPOINTEP : READ iU,POI 

DATA* THEN 40 



ists 

f ij 1 1 



= BA 
i n t. e 
he r, 
DATA 
NTER 



EP 



1 . 1. 4 i 

SINTER 

list t ■: 
data . 



nex tpo inter, da T* 



NEWOATA* 
1 e merit p.; 
place to 
record i 
NEXTFREE! 



l n k 
. bv 



in D, 
.i n t e d 

physical 1 v 
u t o f t h e \- 
MEXTRECOED 
P I N T E R = P INT E R , t h e 
i e d i n o r d e r t o a d d 
POINTEROPQINTER THE 
- 1; NEXTFREE- NEXTRE 
- MEX TFREE : BASEPO I N T 

record out of free 
, 1 ; BASEPO I NTER- MEX 

1 1. e new i t e m p o i ri t 
to bv TRAILPOINTER p 
to bv TRAILPOINTER p 
-MEXTEREE; POINTER, 
, TRAILPOINTER; MEXT'F 



ills 
TRAIL 

.it th 

?e 1 i 

the 
t f h e 

75 
3RD 
v, NE 
inked 
;ECOR 
:■, in h e 
i nter 
i. n t t 
;WDAT 
£E- P 



INTER. 

ne 1.1.1 re 
e d lis 



t. 



i n t « 

L r, Si . 



ATAS! 

I 1 5 t . 

? the r 
make t 
n e uj 1 1 • 

: r WDATA* 



he re 



list. When deleting a record from the 
ordered list, the record that has just 
been removed is added to the linked 
list of free records so that it can be 
used the next time an element is to be 
added. 

The following example uses linked 
lists and random-access files. For the 
sake of simplicity, assume that each 
record consists of one pointer to the 
next record in the list and one string 
of data. Since there are two linked 
lists, the first logical record will con- 
tain two pointers, one to the first data 
element, the second to the first free 
record. 

The program of listing 1, written in 
CBASIC, creates a data file capable 
of holding ten data entries of fourteen 
characters each. The file created by 
this program is shown in listing 5a. 
Notice that data record number two, 
the first in the linked list of data, has 
a zero for its forward pointer and is 
filled with "z"s, the highest possible 
data going in alphabetical order. 
Such a dummy record, usually called 
a sentinel, will always be the last ele- 
ment of the linked list. The sentinel is 
also used to locate the end of the link- 
ed list when the linked list is traversed 
in ascending order. Although pro- 
grams can be written without the sen- 
tinel record, the sentinel greatly 
simplifies them. 

The program of listing 2 adds a 
record to the linked list. It gets the 
data to be added and scans the linked 
list (keeping a pointer to the previous 
record) until the record to be added is 
alphabetically less than the one being 
read. When this occurs, the new item 
should be added immediately before 
the one being read. This is accom- 
plished by making the new record 
point to the record being read and 
making the previous record point to 
the new record. When inserting a new 
item at the very beginning of the link- 
ed list, a special case exists that must 
be accounted for, since the base 
pointer in the first record must be 
changed to point to the new record. 

Listing 5b shows what the data 
looks like after adding a piece of data 
named "First item". Listing 5c and 
listing 5d show the contents of the file 
after the addition of several new en- 
tries to the file. Note that the path of 
the linked list is such that the data is 
always in alphabetical order. 



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Listing 3: Program to list a linked-list file. This program uses the forward pointers to 
print out the records in the order in which they are encountered. This example cor- 
responds to printing out the data fields in ascending alphabetic order. 

REM THIS PROGRAM LISTS OUR ALREADY SORTED FILE. 

REM 

REM — Open tile #1. with record length of 22. 
10 OPEN "DATA.. F I L " RECL 22 AS 1 

REM — Set pointer to start of linked list, 
15 READ ftl, I! POINTER 

REM— Loot" to traverse list and print data 

REM — until POINTER is zero. 
20 READ # 1 , PO I NTER ; pn I NTER , DATA* 
25 IF POINTERO--0 THEN PRINT DATA* : GOTO 20 
30 CLOSE 1 



Listing 4: Program to delete a record from a linked list file. This program deletes a given 
record by changing the pointer of its previous record. The pointers in record 1 and the 
deleted record are changed so that this record is the first record of the linked group of 
free (available) records. 





REM 


DELETE A Di 




REM 
REM 
REM 


ADD I T TO i 








REM-- 


-Open file : 


1 




OPEN "DATA 


15 




INPUT "Data 




RE11- 


-Left justi 


20 




DATA*=LEFT 




R'EM- 


-Set points 


25 




READ #1,1: 


30 




POINTER=Bfi: 




REM- 


-Search loo 




REM- 


-finds a ma 


35 




TRAILPOINTI 


40 




POINTER-NE 


45 




READ ttl,PO 


50 




IE NEXTPOI 


55 




IF DATA IN* 




REM- 


-Delete the 




REM- 


- r e r o r d P o i 




REM- 


-after the 


60 




IF TRAILPO 
ELSE PR 




REM- 


-Add the noi 




REM- 


■- f r e e 1 l n k e 


65 




PRINT #l,pi 


70 




PRINT #1,1 


75 




CLOSE t 



DATA ITEM FROM OUR MAIN LI NEED LIS! AMD 
rO OUR LINKED LIST OF FPEE RECORDS. 



#1 with record length of 22, 
.FIL" RECL 22 AS 1 

to delete: ": DAT AS, 
f v d a t a in a f 1 e 1 d o f 1 1 a n k s . 
*<DATA*+" ". 14) 

r s t o b e 9 i n n i n s o f 1 i n k e d list 

BASEPO INTER, NEXTPREE 
SFPO I NTER : NEXTPO I NTER=BASE PO I 
p t r a v e r s e s t h e 1 i n k-e d 1 i s t u n 
tch or runs oi.it of data, 
ER=PO I NTER : PRCVDA7 A*=DATAI N* 
XT POINTER 

I NTER : NE X "1 PO T NTER , DATA I N4 
NTER-0 THEN PRJNT"No match hxi 
■ODATA4 THEN 35 

record pointed to bY POINTER 
nted to hv TRAILPO INTER point 
one pointed to by PO I NTER . 
IN"1ER=P0INTER THEM BASEPO I NTER 
INT #1 , TRAILPOINTER: NEXTPOI NT 
ui u n u s e d r e c o r i J p o i n t e d t o b t 
d list. 

01 NTER: NEXTFREE, "" 
: BASEPO I NTER, POINTER 



NT El 

t i 1 



GOTO 



mak 
the 



] n g I: 
r e c o i 



NE 
ER, 



nf.: 



■0 [NIL 
:EVDAT 



r- d 

R \ 

A* 

the 



The program of listing 3 and its 
output in listing 5e will clarify any 
confusion in following the list. This 
program traverses the linked list of 
data and prints each item out as it is 
read. It can be concluded, from the 
brevity of listing 3, that printing a 
sorted list is much easier with the use 
of a linked-list file organization. 

Listing 4 shows the solution to the 
problem of deleting a given data item 
and placing the free space back into 
the linked list of free records. The 
program scans the linked list until it 
reaches the end of the file or finds the 
data to be deleted. When the data to 
be deleted has been found, the pre- 
vious record is made to point to 
where the deleted record points. As in 
listing 2, deleting the first item in the 
linked list results in a special case, 
and the base pointer must be modi- 
fied. The deleted record is then added 
to the linked list of free records. 
Listing 5f shows the data file after the 
"Fourth" data item has been deleted. 
Note the "6" in the first line of listing 
5f, which points to the first free 
record, the record that has just been 
deleted. 

Although the concept of the linked 
list may be difficult to understand, it 
is a very powerful tool. If, in the 
mailing list example, the information 
needs to be sorted by more than one 
field, it is simple to create a linked list 
for each field to be sorted and to 
make room for the additional 
pointers. 

Other modifications are possible; 
for example, the linked list could 
spread over more than one file on a 
disk or over more than one disk by 
having the pointers preceded by a 



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100 February 1980 © BYTE Publications Inc 



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BYTE February 1980 101 



Listing 5: Examples of linked list files. The contents of the file created by listing 1 are 
shown in listings 5a, 5b, 5c, 5d, and 5f. In each case, the records are numbered 1 
through 12, with record 1 at the top. Listing 5a shows the contents of the file just after it 
has been created by the program in listing 1. Listings 5b, 5c, and 5d show the file after 
one, two, and five records, respectively, have been added. Listing 5e shows the result of 
running the program of listing 3. The data appears listed in ascending alphabetic se- 
quence. Listing 5f shows the file after the fourth node has been deleted. Note that the 
available record pointer in record 1 points to line 6, the location of the line that has just 
been deleted. 



(5a) 



(5c) 



1 , 

1 1 , 
1 2 , 



0, ZZZZ3Z! 2 zzzs 
4 i " F i r ? I; ] tern 
2» "Se co rid i fern 

6, " " 

7, " " 



10, "" 

11, "" 

12, "" 

0, " " 



(5e) A>R2 LIST 

CRUN VER 2.04 

Fifth 

First item 
Fourth 
Second i tern 
Third 



digit specifying the file or disk-drive 
number. A slightly better solution for 
very large data bases is to use 
pointers to create a tree structure. 
However, operations involving trees 
are very involved, and a discussion of 
them is outside the scope of this arti- 
cle. Those interested in this subject 
are encouraged to read the book 
Algorithms + Data Structures = 
Programs by Niklaus Wirth, listed in 
the references. 



(5b) 3,4 

2. "First i 



10, 
1 1 , 
1 2 , 



(5d) 



(5f) 



Oj 


'zzzrzz? 


Z Z 7 2 Z Z Z ' 


6, 


1 p i r s t j 


tern 


5, 


'Second 


item 


2, 


'Third 




4, 


'Fourth 




'■? ■, 


' F i f t h 




10 
11 


;„„ 




0, 







7,6 

4- "First item 
5, "Second i tern 
2, "Third 



'Fifth 



10, 
1 1, 
1 2 , 
0, " 



Uses of the Linked List 

The concepts of linked lists and 
pointers can also be used to handle 
data that has a variable amount of 
additional information associated 
with it. One particular problem that 
is unmanageable without linked lists 
involves a theatre-booking program 
where you have a movie film and an 
unknown, highly variable number of 
dates for which it is scheduled to be 
used. Because of the uncertainty 



The concepts of linked lists 
and pointers can also be 
used to handle data that 
has a variable amount of 
additional information 
associated with it. 

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIHIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII 

involved with the scheduling process, 
it is usually unacceptable to either 
limit the number of dates that can be 
associated with a film or to reserve 
enough space per film to handle even 
the most heavily scheduled film. 

One solution to this scheduling 
problem makes use of a linked list. A 
file containing the essential informa- 
tion for each film can also have, for 
each record describing a film, a 
pointer that points to a linked list of 
date records (each record containing 
a date and its associated infor- 
mation). Traversing the linked list of 
dates for any one film is both fast and 
easy, and each film takes up only as 
much space for date records as is 
needed. 

The programs and ideas presented 
here can be converted to work in any 
programming language that allows 
some sort of random-access files. In 
cases where a linked list is applicable, 
necessity for the additional storage 
space for the pointers and the slightly 
increased program complexity are 
both far outweighed by the ability to 
directly access related data items with 
a minimum of searching and sorting. 

The difficulty arises in determining 
whether or not to use linked lists in a 
particular application. There are, 
unfortunately, no fixed criteria since 
the choice of a method will depend on 
such factors as the computer's disk 
capabilities, the number of data 
items, the length of the data items, 
how often the data will be sorted, and 
how often the data base will change. 
You should, however, plan the data 
base before doing any programming, 
taking into account the possible 
methods and the tradeoffs 
involved. ■ 



REFERENCES 

1. Grogono, Peter, Programming in Pascal, 
Addison-Wesley, Reading MA, 1973. 

2. Wirth, Niklaus, Algorithms + Data Struc- 
tures = Programs, Prentice-Hall, Englewood 
Cliffs NJ, 1976. 



102 February 1980 © BYTE Publications Inc 




INTROL/X-IO. 



COMPUTERIZE YOUR HOME. 

The lntrol/X-10 peripheral system for your Apple* 
Computer allows you to remotely control lights and 
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READY TO USE. 

lntrol/X-10 comes with complete software to control 
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date for a particular event. • Specify an interval of time for 
an event. • Rate device wattages for a running account 
of power consumption during your schedule for energy 
management. • Used with our Apple Clock™ your sched- 
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may run at the same time in "foreground." 



EVERYTHING YOU NEED. 

The Introl Controller board plugs into a peripheral slot 
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BYTE February 1980 103 



PUT YOUR IDEAS 




(0 1 979 Terak Corporation 



IN MOTION FOR $7850. 




Invest in a Terak 85 1 0/a desk top 
graphics computer for only $7,850, and 
you'll get the performance of systems 
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The Terak is based on a powerful DEC 
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The Terak operates in either stand-alone 
or on-line environments, and is fully 
compatible with DEC hardware. 

An independently controlled 4K 
read/write memory allows the creation of 
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set that may be required. 

There's more. A two-port memory 
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The best part is the software. Terak 
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These are actual unretouched photos. 



*A trademark of Digital Equipment Corp. 
C *A trademark of the Regents of the University of California. 

©I 979 Terak Corporation 
Animation by Michael Smith, 
University of Utah. 
Computer Aided Instruction Group. 



A Fast, Multibyte Binary to 

Binary-Coded-Decimal 

Conversion Routine 



Michael R McQuade 
School of Electrical Engineering 

Van Leer Building 
Georgia Institute of Technology 

Atlanta GA 30332 



A problem which has confronted users of small com- 
puter systems over the years has been the incompatibility 
of the number representation required by output devices 
and that used for internal processing. Output devices 
used by the small systems need to receive binary-coded- 
decimal (BCD) or ASCII (American Standard Code for 
Information Interchange) data representations, while the 
microprocessor is most efficient when handling a straight 
binary number. Several solutions to the problem exist, 
and as would be expected, each has its own advantages 
and disadvantages. 

Some users choose to initially store all numbers in their 
binary-coded-decimal representation and do all subse- 
quent processing in this format. This has the advantage 
of easy and quick conversion of the numbers into the re- 
quired output format. At worst, the binary-coded- 
decimal represented number must be converted to an 
ASCII format. This requires attaching a fixed 4-bit prefix 
to each binary-coded-decimal digit. 

A disadvantage associated with this approach is that 
arithmetic operations take longer to perform, since the 
results must be decimally adjusted after each operation. 
Also, more memory is required to store the binary- 
coded-decimal form of the number than is required for its 
straight binary equivalent. A direct result of this in- 
creased memory requirement is the need to perform more 



About the Author 

Mike McQuade is currently working towards a PhD degree in the 
Computer Architecture Laboratory at the School of Electrical Engineer- 
ing at the Georgia Institute of Technology. He has instructed computer 
courses there, and has taught short microprocessor courses for the In- 
stitute of Electrical and Electronics Engineers at both national and 
regional levels. 



memory-access operations to transfer the numbers into 
and out of the processor. Memory accesses are a very 
time-consuming operation. 

For the users who choose a straight, binary-number 
representation for internal storage, the advantages of effi- 
cient memory utilization and straightforward arithmetic 
are gained. The question of how to convert the numbers 
to an acceptable output format for the display device still 
remains to be answered. This question basically reduces 
down to converting the binary numbers to binary -coded- 
decimal form. 

Methods of Conversion 

There are three basic approaches in wide use. 
The first approach is to count the binary number down to 
while incrementing its binary-coded-decimal counter- 
part up from using modulo-10 counting. Modulo-10 
counting performs a decimal-adjust operation after each 
incremental addition. This method is conceptually easy 
and requires a minimum of program code if the micro- 
processor has a decimal-adjust instruction. The counting 
method can, however, be very time-consuming if large 
numbers are being converted. For some applications this 
time penalty would be irrelevant (eg: if the output device 
is very slow when compared to the processor's cycle 
time). For a slow output device, any time savings realized 
by using a faster conversion routine usually has to be 
wasted in a wait loop. 

The second approach is to use some form of table 
lookup routine. Assuming that the table is extensive 
enough, the lookup technique performs a very fast con- 
version. The drawback to this technique is that as the size 
of the numbers being handled gets larger, either a great 
deal of memory must be dedicated to the table, or some 
type of divide-with-remainder scheme must be imple- 



106 February 1980 © BYTE Publications Inc 



WHY DOESN'T 



COMPUTER 
SPECIALIST 
MOVE TO 
HUGHES IN 
SOUTHERN 
CALIFORNIA? 




We need you. But frankly, not everybody you meet 
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Analyze and determine system software requirements 
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Concentrate on support software, operating program 
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Help advance the state of test control software and 
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System Evaluation 

Develop application software for analyzing test data 
to improve system performance. 

Altogether, the growing Hughes population of computer 
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tems engineers; systems analysts; applications, diag- 
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There's a place for you in our marvelous working 
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You bring the focused imagination. Is it a deal? 

First, send us a resume showing your past salaries 
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merited. The division scheme allows the table size to re- 
main small, but it causes the conversion time to increase. 
As was pointed out earlier, this may not be important, li- 
the processor being used does not have a decimal-adjust 
instruction and the numbers encountered are not too 
large, this second method is very popular. 

The third approach in converting from straight binary 
to binary-coded decimal is to use an algorithm based on 
the structure of the binary number system. Given the 
binary number: 

b„ b„_, b„_ 2 . . . b 2 b t b 

where each of the bs can represent either a 1 or a 0, and b„ 
is the most significant bit, it can be expanded as: 



b„ X 2" + b,,., X 2-' + 



+ b, X 2 1 + b X 2° 
(Form I). 



Form I is not conducive to an iterative-type binary to 
binary-coded decimal conversion routine, but can be 
rewritten as: 



(. . .((b„ X 2) + b,,.,) X 2 + 



+ b,) X 2 + b„ 
(Form II) 



Form II contains only the decimal numbers 0, 1, and 2, 
which have the same representations in either straight 
binary or binary-coded decimal. Straight binary and 
binary-coded-decimal representations of a number differ 
only for numbers greater than 9. While straight binary 
adheres strictly to position weighting in powers of 2, 
binary-coded decimal treats each decimal digit of the 
number independently and represents it as a 4-bit straight 
binary number. 

If Form II is implemented using binary-coded-decimal 
arithmetic (performing a decimal adjust after each addi- 
tion), the final result will be in binary-coded-decimal 
representation. Form II lends itself to an iterative-type 
implementation which allows it to be coded to easily 
accommodate any size number. 



Carry 




1 
1 



Auxiliary Carry 


1 


1 



Correction Factor 

10011010 
10100000 
11111010 
00000000 



Table 1: Correction factors in binary for the binary to binary- 
coded-decimal (BCD) conversion algorithm. 



Much has been said about performing a decimal-adjust 
operation when operating on numbers in the binary- 
coded-decimal format. When two binary-coded-decimal 
numbers are added by the processor's straight binary- 
adding accumulator, the result is not in binary-coded- 
decimal form. It is necessary to perform one more opera- 
tion after each addition to correct for the fact that the 
processor's arithmetic logic is designed to add straight 
binary numbers. This extra operation is the decimal ad- 
just. Many of the microprocessors on the market today 
have the decimal-adjust operation contained in their in- 
struction sets. 

If the processor being used does not contain a decimal- 
adjust instruction, it is still possible to perform a decimal- 
adjust operation. What must be done is to allow for the 
fact that a binary-coded-decimal number uses only ten of 
the sixteen possible 4-bit combinations for each digit. If 
two binary-coded-decimal numbers are added together, 
and the least significant 4 bits of the result have a value 
greater than 9, then 6 must be added to the result. It is 
necessary to add 6 to skip over the six unallowed BCD bit 
combinations. The next 4 bits of the result are then 
tested, and 6 is added to them if necessary. This is 
repeated across the entire result. 

A Better Method 

The above method works in theory but is rather 
awkward to program. Let us examine a method based on 
the above theory which lends itself to straightforward 
programming. The method will be for 8-bit processors, 



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108 February 1980 ® BYTE Publications Inc 



Circle 66 on inquiry card. 



Telecommunications R&D 
Software Engineers 

Reaching Out To The Challenge 
of Our Environment . . . 

San Francisco Peninsula 



Designing the world's most advanced computer-controlled telephone systems and office of 
the future products requires the world's finest talent: Yours. 

Your Ideas Count 

Help prepare for the future at BNR INC., a center of excellence in structured software design 
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Of 



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The R&D Laboratory for 
Northern Telecom and Bell Canada 



BYTE February 1980 



Listing 1: The multibyte binary to binary-coded-decimal (BCD) 
conversion algorithm coded as a subroutine for the 8080 
microprocessor. 



THE SUBROUTIICS ALWAYS SAVE TIC CONTENTS OF REGISTERS A 
D E H L AND THE STATUS FLflGS. IF THE CONTENTS OF REGISTERS 
B C NEED TO BE SRVED THE CALLING ROUTINE MUST EXPLICITLY DO IT. 



,*********** 



»8INARY TO BCD CONVERSION SUBROUTINE' 



THE SUBROUTINE CONVERTS ft MULTI-BYTE BINARY NUMBER TO ITS EQUIVALENT 
MULTI-BYTE BINARY CODED DECIMAL (BCD) REPRESENTATION THE BYTES 
OF BOTH NUMBERS ARE STORED IN MEMORY IN ASCENDING ORDER WITH 
THE LEOST SIGNIFICflNT BYTE IN THE LOW DC OF THE MEMORY STftCK. THE 
REQUIRED PARAMETERS NEEDED TO BE PftSSED RRE: 

H L GETS ADDRESS OF LOU ORDER BYTE OF BINARY NUMBER 
D GTS NUMBER OF BYTES IN BINARY NUMBER 
E GETS NUMBER OF BYTES IN BCD RESULT AREA 

THE SUBROUTINE ASSUMES THAT THE BINARY HUMBER HILL FIT IK THE SUPPLIED 
NUMBER OF BCD BYTES. THE ROUTINE UILL FILL IN THE BCD BYTES WITH 
LEADING ZEROS IF NECESSARY. 



eeee F5 


BNBCD: 


PUSH 


PSH 


SAVE STATUS 


eeei « 




NOV 


C,E 


COPY 1 BCD BYTES TO C 


8882 E5 




PUSH 


H 


SAVE ADDR OF BINARY # ON STACK 


9883 216488 




LXI 


H.BCDNL 


LOAD HL WITH ADDR OF BCD t 


vOPQ MlffO 


LflB16: 


HVI 


0,8 


ZERO OUT MEMORY LOCATION 


8888 23 




I NX 


H 


INCREMENT HL 


8889 BD 




OCR 


C 


DECREMENT C 


MR C286B8 




JNZ 


LRB16 


IF C=8 BRANCH FROM LOOP 


888D 7R 




MOV 


fl,D 


PUT 1 OF BINARY BYTES IN A 


986E 87 




ROC 


A 




B88F87 




ADC 


A 


MULTIPLY BY 8 TO GET 1 OF BITS 


8818 87 




ADD 


A 




8811 47 




MOV 


B,A 


STORE 1 OF BITS IN B 


8812 AF 




XRfl 


A 


SET CARRY TO ZERO 


8813 4A 


MLOOP 


MOV 


CD 


PUT 1 OF BINARY BYTES IN C 



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8814 El 




POP 


H 


RESTORE ADDR OF BINARY 1 TO HL 


8815 3B 




OCX 


SP 




8816 3B 




DCX 


SP 


LEAVE HL ON STftCK 


8817 7E 


RLOOP: 


MOV 


A,M 


PUT BINARY BYTE IN A 


8818 8F 




ADC 


ft 


SHIFT BYTE LEFT t FILL KITH CflRRY 


8819 77 




NOV 


H,fl 


REPLflCEBYTE 


881ft 8D 




DCR 


C 


DECREMENT C 


991B CR22B8 




JZ 


LftB17 


BRflHCH FROM LOOP IF LftST BYTE 


881E 23 




I NX 


H 


INCREMENT HL 


881F C31788 




JHP 


RLOOP 


JUMP TO STRRT OF ROTATE LOOP 


8822 El 


LBB17: 


POP 


H 


RESTORE HL POINTER TO LOW ORDER BINARY BYTE 


8823 38 




DCX 


SP 




8824 36 




DCX 


SP 


LERVEHL ON STftCK 


8825D22988 




JNC 


LAB18 


SKIP FILL HITH ONE IF NO CfiRRY 


8828 34 




INR 


M 


FILL HITH ONE 


8829 4B 


LBB18. 


MOV 


C,E 


PUT 1 OF BCD BYTE IN C 


882A 216488 




LXI 


H.BCDNL 


LOAD HL WITH RDDR OF BCD 


882D 3E88 


LftB28: 


MVI 


ft, 8 


ZERO OUT R 


882F BE 




ADC 


M 


ADD BCD BYTE TO A WITH CftRRY 


8838 27 




DBA 




CONVERT RESULT TO BCD 


8831 77 




MOV 


M,A 


SAVE NEW BCD BYTE 


8832 D23R88 




JNC 


LftB19 


SKIP REST IF NO CARRY 


8835 23 




I NX 


H 


POINT TO NEXT BCD BYTE 


8836 8D 




DCR 


C 


DECREMENT C 


8837 C22D88 




JNZ 


LflB28 


IF C=8 LEAVE LOOP 


883ft 46 


LHB19: 


MOV 


C,E 


PUT 1 OF BCD BYTE IN C 


883B 85 




DCR 


B 


DECREMENT BIT COUNT 


883C Cfl4E88 




JZ 


LAB48 


EXIT MfilN LOOP IF COUNT = 8 


883F 216488 




LXI 


HBCDNL 


LOAD HL WITH RDDR OF BCD 
CflRRY=« ENTERING NEXT LOOP WHICH 
MULTIPLIES BCD 1 BY TWO 


8842 7E 


LflB21: 


MOV 


ft,M 


, PUT BCD BYTE IN ft 


8843 8E 




ADC 


M 


; ADD BCD BYTE TO ITSELF WITH CflRRY 


8844 27 




DftA 




I CONVERT RESULT TO BCD 


8845 77 




MOV 


N,A 


iSAVE NEW BCD BYTE 


8846 23 




I NX 


H 


; POINT TO NEXT BCD BYTE 


8847 8D 




DCR 


C 


i DECREMENT C 


8848 C24288 




JNZ 


LAB21 


i IF C=8 LEftVE LOOP 


884B C31388 




JMP 


MLOOP 


;D0 FOR ALL BITS OF BINARY 1 


884E El 


LAB48: 


POP 


H 


i RESTORE HL 


884F Fl 




POP 


PSW 


; RESTORE STfiTUS 


8858 C9 




RET 




1 RETURN 



since they are the most popular. First it is necessary to 
keep track not only of the carry out of the eighth bit posi- 
tion, but also the carry from the fourth to fifth bit posi- 
tion. This second carry will be referred to as the auxiliary 
carry. 

(1) Add the binary number 01100110 to the first 
number. 

(2) Add the second number to the result generated in 
step 1. Keep track of both the carry and auxiliary 
carry from this addition. The carry generated 
here is the true carry to the next higher digit. 

(3) Based on the carry and auxiliary carry generated 
in step 2, add one of the correction factors shown 
in table 1 to the result of step 2. 

The result has now been decimally adjusted. 

The program shown in listing 1 and the flowchart 
shown in figure 1 provide an implementation of Form II 
using binary-coded-decimal arithmetic for the Intel 8080 
microprocessor. It uses the decimal-adjust (DAA) in- 
struction in the 8080's instruction set. A simple program 
shown in listing 2 converts data from binary-coded 
decimal to ASCII representation. The conversion from 
binary-coded-decimal to ASCII entails taking each of the 
two 4-bit, binary-coded-decimal digits, putting them in a 
byte, and appending the binary prefix 0011. Both pro- 
grams are coded as subroutines, since these forms are 
usually more convenient to include in larger programs. 

The binary-to-binary-coded-decimal subroutine of 



110 February 1980 © BYTE Publications lnc 



Circle 67 on inquiry card. 




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Apple 1 1 32 K with Applesoft Basic 
Apple II 16K Micro with Applesoft 
ROM Card 



$35 



MICRO TAX II 

Form 1040 

Schedule A 

Schedule B 

Schedule G (Inc. Avg.) 

Schedule TC 

Form 4625 (Minimum Tax) 

Form 4726 (Max Tax) 

Form 6251 (Alt. Min. Tax) 

yVardvdrlt 
Software 



MICRO TAX III $50 

Program 2 plus 
Schedule C 
Schedule D 
Schedule E 
Schedule SE 
Form 2119 - Sale of 
Personal Residence 



Coming Soon - Micro Tax 
Package for PETand Tl 
Systems. 



P.O. Box 26505 Milwaukee, Wl 53213 

24hrs. Call TOLL FREE 1-800-558-8570. 7 days 

In Wisconsin 1-414-289-9988 

©Aardvark Software Inc. 1979 



VISA 



Circle 68 on inquiry card. 



PUZZLE YOUR COMPUTER 

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Minicrossword 

Two Minicrossword programs invent crossword puzzles 
and display them on the screen. Words are drawn 
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Two Codeword puzzles on the same cassette use the 
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for adults and high schoolers. 
TRS-80 Level II (16K), or APPLE II Applesoft $14.95 



T G I I T 


H fit 


I L 


A M 


n * u „. 




Y B N X M 
N U L Z T 
T S E S Q 


B 
D 
J 


D 
D 
R 


K G 
X 
D 


1 « J R u 
N M U Y Y H 
x L I S A H 
K Z R G If U 


A H X G K 


H 


A 


H C 


A V 


OBAN 


L S A U D 


I 


A 


R A 


B I 


A G B M 


A U IS S V 


F 


P 


N R 


M L 


B M P U 


U L E X Q 


F 


Z 


A d 


P Y 


H B N J 


W I K Q F 





Z 


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J D M T R 


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E Z R I 


H M J M L 


c 





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5 WORDS-GUESS? ?_ 



Astro Word 
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The computer makes hundreds of the popular 
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Look for these titles at your participating 
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Master Charge, Visa. Add 5% shipping. 



Circle 69 on inquiry card. 




f BNBCD J 



INITIALIZE BCD 
NUMBER TO ZERO 



INITIALIZE BIT 
COUNTER 8 X D 



ROTATE BINARY NUMBER 
LEFT WITH COPY OF 
MOST SIGNIFICANT BIT 
IN CARRY 



GET LEAST 
SIGNIFICANT BYTE 
OF BCD NUMBER 



1 



ADD CARRY TO 
BYTE USING 
BCD ARITHMETIC 



GET NEXT 
BINARY-CODED 
DECIMAL BYTE 




YES 



YES 



GET LEAST 
SIGNIFICANT BYTE 
OF BCD NUMBER 



ADD BYTE TO ITSELF 
WITH CARRY USING 
BCD ARITHMETIC 




DECREMENT 
BIT COUNTER 



GET NEXT BCD BYTE 




( RETURN ) 



Figure 1: Flowchart of the algorithm for the binary to binary- 
coded-decimal (BCD) conversion subroutine. 



listing 1 requires contiguous memory locations to hold 
the binary-coded-decimal result. The address of the 
memory location for the low-order byte of the binary- 
coded-decimal number has been labeled BCDNL (binary- 
coded-decimal number location) in the subroutine. The 



112 February 1980 @ BYTE Publications Inc 



HI THERE! 



It has come to our attention that many of our customers are not aware 
of the wide variety of products we have available. Following is a list 
of all our current major products and prices. Watch BYTE for new items, 



Part No. 

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Tarbell BASIC source on 2 CP/M disks 
Proc Tech Assembler/Editor with listing 
EMPL micro APL on cassette & instructions 
EMPL micro APL on CP/M disk & instructions 
CP/M 2.0 Operating system incl documentation 
CP/M 1.4 Operating system incl BASIC-E on disk 
CP/M 1.4 on soft-sectored MINI-FLOPPY disk 
CP/M 1.4 Operating system manual set (of six) 
BASIC-E Compiler Manual (works with CP/M) 
BASIC-E Source Listing (in PL/M) 
Public Domain Disk #1 - includes DISKTEST, 
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CBASIC-2 disk 85 

CBASIC-2 manual 15 

KLH Systems Spooler for CP/M on disk 70 

FAST! Screen-oriented Editor/Assembler for CP/M 100 
Software to operate D.C. Hayes Modem Remote 195 
Screen-Oriented CP/M Editor 135 

Meta-Tech Pascal Compiler for CP/M 99 



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Prices are subject to change without notice. 

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For guick delivery, see your local Tarbell dealer. 




Circle 70 on inquiry card. 

950 Dovlen Place, Suite B 
Carson, California 90746 



(213) 538-4251 
(213) 538-2254 



Listing 2: A subroutine to convert a single-byte, 2-digit, binary- 
coded-decimal number to two single-byte ASCII characters, 
coded for the 8080 microprocessor. 



TO RSCII SUBROUTINE* 



******* 



;THE SUBROUTINE TAKES A TMO DIGIT BCD NUnKR IN MEHORV POINTED TO BY 

iHL AM) CONVERTS IT TO ASCII. THE MOST SIGNIFICANT DIGIT IS PUT 

I IN REGISTER B WILE THE LEflST SIGNIFICANT DIGIT IS PUT IN REGISTER C. 



6851 F5 ASCII: PUSH 


PSH 


SAVE STATUS 


8852 3E8F 


M 


H99891111B 


PUT LEAST SIGNIFICANT DIGIT MASK IN A 


9854 AC 


AHA 


n 


MASK OFF LEAST SIGNIFICANT DIGIT 


9855 F638 


ORI 


eeiieeeee 


CONVERT TO ASCII 


9857 4F 


NOV 


C,A 


PUT IN REG C 


9858 3EF8 


11VI 


fbuueeeee 


PUT MOST SIGNIFICANT DIGIT MASK IN A 


985A At 


ANA 


M 


MASK OFF HOST SIGNIFICANT DIGIT 


985B 9F 


RRC 






985C 9F 


RRC 






9850 BF 


RRC 






985E OF 


RRC 




ROTATE RIGHT FOUR PLACES 


985F FR8 


ORI 


981188996 


CONVERT TO ASCII 


8861 47 


HOV 


B,R 


PUT IN REG B 


8962 Fl 


POP 


PSH 


RESTORE STATUS 


8863 C9 


RET 




RETURN 


8964 BCDNL: DS 


31 


START OF BCD NUMBER 


0800 


END 







number is ordered upwards in memory. Register E must 
contain the number of bytes in the binary-coded-decimal 
number when the subroutine is called. If more bytes are 
specified than are needed, the extra will be filled with 
leading zeros. 

The other parameters which must be passed to the 
subroutine are the number of bytes in the binary number 
and the address of the low-order byte of the binary 



number. The number of bytes in the binary number is to 
be in register D, while the address of the low-order byte is 
in register pair HL. The binary number is assumed to be 
stored in memory using the same convention as the 
binary-coded-decimal number. The more significant 
bytes are found at increasing memory addresses. 

By having register pair HL point to the binary number, 
the routine can be used to convert all binary numbers re- 
quired by the user's program without moving them to a 
specific location. All results are put in the same location, 
since this is temporary storage needed only until the 
number is sent to the display device. 

The binary to binary-coded-decimal conversion sub- 
routine provided can handle binary numbers of any 
length up to and including 31 bytes. This corresponds to 
a decimal number in excess of 4.5 X 10 74 with a full 75 
significant digits. This should be adequate to handle any 
physical quantity encountered. To establish a reference, 
it is only about 1.5 X 10 21 angstroms from the earth to 
the sun. (An angstrom is one ten-billionth of a meter, that 
is 1/10 9 , and is normally used to measure the wavelength 
of light.) 

The routines provided have been tested using a high- 
speed line printer as an output device. The routines were 
fast enough to allow the line printer not to wait when 
being sent a stream of 6-digit numbers. While the routines 
have been tested and were fast enough for the desired 
applications, an extensive effort was not made to 
eliminate every unneeded processor cycle. The object 
code provided in listings 1 and 2 will also execute on an 
Intel 8085 or a Zilog Z80 microprocessor. ■ 



§^ 



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114 February 1980 © BYTE Publications lnc 



Circle 71 on inquiry card. 




"Superbrain is a registered trademark of Intertec Data Systems. 



System Specifications 



Microprocessors 



Word Size 
Execution Time 
Machine Instructions 
Interrupt Mode 
Floppy Disk 

Storage Capacity 

Data Transfer Rate 
Average Access Time 
Media 

Disk Rolation 
Interna] Memory 
Dynamic RAM 
Static RAM 

ROM Siorage 

CRT 

Display Size 

Display Format 

Character Font 

Line Drawing Character: 

Display Presentation 

Bandwidth 

Cursor 
Communications 

Screen Data Transfer 

Auxiliary Interface 

Parallel Interface 

S- 100 Bus 

Transparent Mode 

Parity 

Transmission Mode 

Addressable Cursor 
System Utilities 

Disk Operating System 

DOS Software 
Optional Software 

FORTRAN 

COBOL 

BASIC 

Application Packages 



Keyboard 

Alphanumeric Character 
Special Features 
Numeric Pad 
Special Functions Keys 
Cursor Control 
Internal Construction 
Cabinetry 
Component Layout 



Twin Z80A's with 4MH2 Clock Frequency One Z80A (the host processor) perlorms all 

processor and screen related functions The second Z80A is "down-loaded" by (he host to 

execute disk I/O When not processing disk data, the second Z80 may be programmed by 

the host for other processor related functions 

8 bits 

1 microseconds register to register 

158 

All interrupts are vectored 

320K tola! bytes formatted on two double density drives Optional external 10-300 

megabyte hard disk storage is available using optional S- 1 00 bus adaptor 

250K bits/second 

250 milliseconds 35 milliseconds track-to-track 

5 ■■'• inch minidisk 

300 RPM 

64K bytes dynamic RAM 

256 bytes of static RAM is provided in addition to the mam processor RAM This memory 

is used for program and/or data storage- for the auxiliary processor 

1 K byles standard Allows ROM "bootstiapping" of system at power-on ROM storage is 

2708 compatible and may be reptogrammed by the user for custom applications 

1 2-mch. dynamically focused P4 phosphor 
25 lines x 80 chaiacters per line 
8x8 character matrix on a 8 x 12 character field 
i Eleven special graphics symbols used loi form generation 
Light characters on a dark background Reversible through keyboard.'piogram selection 
20 MHZ 
Reversed image (block cursor) 

Memory-mapped at 38 kilobaud Serial transmission ol data at rales up to 9600 bps 

Universal RS 232 asynchronous Syncnronous interlace optional 

Radio Shack TRS-80 compatible 

Printed circuit edge connector provided for connection of optional S-100 bus adaptor 

Enables display of all incoming and outgoing control codes 

Choice of even, odd. marking, or spacing 

Hall oi Full Duplex One or two slop bils 

Direct positioning by either discrete oi absolute addressing 

CP'M 

An 8080 disk assembler, debugge: 



text editor and file handling utilities 



Weight 

Physical Dimensions 

Environment 

Power Requirements 



ANSI standard Relocatable, random ar.d sequential disk access 

ANSI standard Relocatable, sequential relative and indexed disk access 

Sequential and random disk access Full string manipulation, interpreter 

Extensive software development tools are available including software for the following 

applications Payroll. Accounts Receivable. Accounts Payable. Inventory Control. General 

Ledger and Word Processing 

Generates all I 28 upper and lower case ASCII characters 

N-Key Rollover Automatic repeal (at 15 CPS), Keyboard lock/unlock 

0-9. decimal point, comma, minus and four user programmable function keys 

Up to 64 user-defined two-key function sequences 

Up. down, forward, backward, and home 

Structural foam 

Two board modular design All processor related functions and hardware are on a single 
printed circuit board All video and power related circuits on a separate single board 
These two boards are interconnected via a single 22-pin ribbon cable 
CRT and two circuit boards mounted to base CRT in a rigid steel frame Disk Drive assem- 
bly mounted into upper cover lor ease of servicing 

Approximately 45 pounds 

14 W (H> x 21 ¥* (W) x 23 /■■ (D) 

Operating 0' to 50' C Storage to 85 C. 10to95%rel humidity - non condensing 

I 1 5 VAC. 60 HZ. I AMP (optional 230VAC SOHZ model available) 

' Specilicitmns suhii't'l '<• Change wilhnul noliti- 



SUPRBRAIIST 

The Honor Graduate 

OEM's... 
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SuperBrain users get exceptional 
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You'll appreciate the careful attention given 
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SuperBrain features include: a full ASCII 
keyboard with numeric pad and user-pro- 
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Circle 72 on inquiry card. 



BYTE February 1980 115 



A Quad Terminal Interface 



Stephen A Alpert 
11 Ridgewood Dr 
Auburn MA 01501 



WORD 
ADDRESS 



5 8 


SITS 
7 


6 




























Every now and then, a micro or mini- 
computer owner may be fortunate enough 
to have more than one terminal and prob- 
ably a modem or two. Unfortunately, there 
never seem to be enough interfaces to 
the computer system to connect all these 



KEYBOARD STATUS 

INTERRUPT ENABLE 
DONE FLAG 

KEYBOARD DATA 
DATA IN LOW BYTE 

PRINTER STATUS 

INTERRUPT ENABLE 
DONE FLAG 

PRINTER DATA 
DATA IN LOW BYTE 



5 8 


7 







I 



5 8 


7 
















Figure I : Addresses required for a single terminal are the low bytes of four 
consecutive words. 



• Each terminal requires four words of 16 bits each. The bits in a word are num- 
bered to 1 5 from right to left. Hence, the low byte in a word contains bits 7 thru 
and the high byte contains bits 1 5 thru 8. 

• The first word contains only two bits of interest. Bit 7, the most significant bit in 
the low byte, is the keyboard done flag. It is set when a byte is received as input. It is 
cleared by a bus initialization (BUS IN IT) or a processor read of the data. Bit 6 is an 
interrupt enable bit for the keyboard. When set, an incoming character will cause an 
automatic vectored interrupt through the processor. 

• The low byte of the second word contains the keyboard data. 

• The third word is arranged like the first word but is used for the printer side of 
the terminal. Bit 7 is set by a bus initialization signal (BUS INIT) or when the inter- 
face can accept another byte from the computer and is cleared when a byte is sent to 
the terminal. 

• The low byte of the fourth word is the data buffer for the printer. 



Table I : Device addressing organization for interface configuration shown in 
figure 7. 



devices into the system at the same time. 
This article chronicles my local solution 
to the problem. 

Through luck and a lot of hard work, 
my computer system consists of a Digital 
Equipment Corporation PDP-11 /1 proc- 
essor, a video monitor, a teleprinter, a 
modem and only one terminal interface. 
Conveniently, the video monitor, which 
serves as the main console, is driven directly 
off the processor. This still meant that 
there was a deficiency of one terminal inter- 
face. 

After reviewing the schematic for the 
interface that I had, I started a design 
to essentially duplicate that board. A 
friend jokingly suggested that a design 
should be generated to drive several ter- 
minals at once. Taking that thought 
seriously, my course of action had been 
charted. 

The creation of this quad terminal 
interface involves ideas applicable to almost 
any sort of processor that uses memory 
addressed IO. That is, the processor contains 
no special IO instructions, but instead 
addresses specific memory addresses to 
communicate with the status registers and 
buffers of the peripheral devices. This trade- 
off means that the devices look like mem- 
ory and the processor can therefore be 
equipped with additional instructions at 
the loss of memory space. 

In the case of the PDP-11 series, the 
processor has a 16 bit data bus and an 
18 bit address bus. In this byte addressable 
machine, the maximum user address space 
is 32 K words. However, the processor 
automatically takes all addresses in the 
range of 160000 to 177777 octal and 
maps them to 760000 to 777777 octal. 
(Digital Equipment Corporation uses octal 
notation in all software.) That means the 
user memory space is limited to 28 K 
words with the addresses generated by 
the processor for 124K to 128K speci- 
fied for the IO page. 



116 February 1980 © BYTE Publications Inc 



About the Author 

Stephen A I pert is an associate professor of computer science at Worcester 
MA Polytechnic Institute. He was the first vice chairman of the ACM 's special 
interest group for minicomputers (SIGMINI) and is a software consultant 
to Digital Equipment Corporation through Hias Inc. He has owned a mini- 
computer since 1973. 

Stephen wishes to thank R Hully, the president of Hias Inc, for the use of 
personnel during construction of this equipment. 



The organization for the device address- 
ing used on the interface in figure 1 is 
summarized in table 1. This structure is 
imposed primarily by the requirement to 
maintain compatibility with the interfaces 
supported by the existing software. Es- 
sentially, the interface should look to 
the software exactly like four separate 
terminal interfaces. A microprocessor could 
easily utilize this memory layout in con- 
secutive bytes in page zero. 

Without the interrupt enable (IE) bit set, 
the keyboard status register must be con- 
stantly checked by the program for the 
presence of a byte of data. This overhead 
is wasteful and serves no utility except in 
the case where the processor has nothing 
else to do. The processor can acknowledge 
an interrupt by automatically jumping to 
a special location in page zero whenever an 
interrupt occurs. A routine must either 
poll the individual devices or, via some kind 
of acknowledge instruction, get information 
off the bus pertaining to an address of the 
desired routine or identification of the 
device requesting the interrupt. This soft- 
ware overhead in a minicomputer makes for 
very inefficient performance. Also, what 
happens when more than one device requests 
service simultaneously? Interrupt masking 
of some sort is needed. What about a 
possible priority based on the requests? 

The PDP-11 processor eliminates these 
problems by utilizing hardware priority 
arbitration and vectored interrupt logic. 
The processor allows four levels of interrupt 
requests and a nonprocessor request mode 
for direct memory access (DMA). Once 
the processor decides to allow an interrupt 
request, it issues a BUS GRANT on one 
of the four lines corresponding to the dif- 
ferent interrupt levels. This grant line is 
fed in sequence from one device to the next. 
Each device that does not want the grant is 
responsible for passing it along to the next 
device as shown in figure 2. In this way, 
the device closest to the processor always 



gets the grant first in the case of simul- 
taneous requests on the same line. After 
the grant has been received by the requesting 
device, that device is responsible for assert- 
ing an interrupt service request and simul- 
taneously asserting a 9 bit address on the 
data lines of the processor's single bus. The 
processor will accept this address not as an 
address of a routine, but rather as a pointer 
to a pair of words. The first word contains 
the address of the interrupt service routine 
and the second word contains a new proc- 
essor status word. The old program counter 
and processor status word are saved on the 
processor's stack. This complete sequencing 
requires approximately 7 /is in the PDP 
11/10. 

From the previous discussion, it is ap- 
parent that the interface must properly 
decode 16 distinct word addresses, four for 
each terminal, along with the proper read 
or write lines. Furthermore, to eliminate 
redundant hardware, and save space on an 
interface board, the logic must do some 
of its own decoding and encoding of ad- 
dresses and data. The program counter and 
Text continued on page 120 



PROCESSOR 



DEVICE #1 



DEVICE #2 



-<. I BUS REQUEST I 
-<^J BUS REQUEST 



I > BUS GRANT I 
BUS GRANT 



n°- 



DEVICE #3 



Figure 2: Typical bus request and grant arrangement with two levels. Re- 
quests are asserted on a particular request line of the processor. Grants are 
generated from the processor and daisy chained through the devices associ- 
ated with that level. 



February 1980 © BYTE Publications Inc 117 




Lgan 



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199 

49 
300 
145 



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390 Java Drive 
Sunnyvale. CA 94086 
(408) 734-9410 



Circle 73 on inquiry card. 



NUMBER 


TYPE 


+ 5V 


GND 


ICI 


74LS266 


1 4 


7 


IC2 


74LS266 


14 


7 


IC3 


7410 


14 


7 


IC4 


7442 


16 


8 


IC5 


7442 


16 


8 


IC6 


74148 


16 


8 


IC7 


7442 


16 


8 


IC8 


74123 


16 


8 


IC9 


7438 


14 


7 


ICIO 


7438 


14 


7 


ICI 1 


NE556 


14 


7 


ICI2 


7493 


5 


10 




BUS TO PRINT BUFFER 
BUS TO PRINT STATUS 
BUS TO KEYBOARD STATUS 
PRINT STATUS TO BUS 
KEYBOARD BUFFER TO BUS 
KEYBOARD STATUS TO BUS 



Figure 3: Address decod- 
ing circuitry. 



Text continued from page 117: 
processor status word for the service rou- 
tines are placed in low memory of addresses 
less than octal 776 by the software and not 
by the hardware. 

The memory words necessary for this 
interface will consist of D type flip flops for 
the status registers since only two bits are 
needed per word. The input and output 
data buffers may be hooked directly to the 
UARTs. UART is, of course, an abbrevia- 
tion for the Universal Asynchronous Re- 
ceiver Transmitter, a device which converts 
parallel bytes of data into a serial stream of 
bits in an industry standard, time ordered 
format. The specific UART used in this 
design is the General Instruments part 
numbered AY-5-1 01 3. 

The address decoding circuitry is shown 
in figure 3. All signals are conditioned by 
bus receivers and are not considered valid 
until the processor asserts a master synchro- 
nization signal (MSYN). The 74LS266 is a 
4 bit digital comparator with open collector 
outputs that are "wire ORed" to detect the 



proper setting of six address lines. The ad- 
dress may be selected by the adjustment 
of the switches. A pair of 7485 magnitude 
comparators could have been used in series 
since they only require a 48 ns delay to 
compare six bits. The MSYN signal is not 
asserted until at least 75 ns after the address 
lines have been activated. Notice the use 
of two 7442s, binary coded decimal de- 
coders. Since all addresses are in consecu- 
tive words, given a base address, say X, the 
first terminal will use addresses X to X+6, 
the second terminal will use addresses 
X+10 to X+16, and so on. IC4 will only 
assert one of its lower four output lines 
if the address is in the range for that ter- 
minal. IC5 is used with the low address 
bits and the read or write control lines 
to indicate which action must be done for 
the specified terminal. Note that the key- 
board data buffer is a "read only" memory 
and the printer data buffer is a "write only" 
memory. 

The UARTs used in this interface re- 
quire a transistor-transistor logic load 



120 February 1980 © BYTE Publications lnc 



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BUS DATA fj>- 
BUS TO STATUS O- 




INT-BACK-L 



B Q 



INTERRUPT BACK 



INTERRUPT 
"O REQUEST 
INT-REQ-L LINE 



NUMBER 


TYPE 


+ 5V 


GND 


ICI 
IC2 


7474 
7411 


14 

14 


7 
7 



Figure 4: The interrupt logic for each UART consists of a pair of these circuits: one for trans- 
mit and one for receive. For the complete interface, eight copies of this circuit are required, so 
the sections of the 7474 circuits are referenced in text by A and B. 



(1.6 mA) for the data inputs and have 
three state data outputs capable of driving 
one transistor-transistor logic load. Since 
the data ports had to be buffered to cor- 
rectly interface to the processor bus, all 
input data ports could be wired in parallel 
and the same for the output data ports. All 
individual signals to and from each UART 
must be conditioned via AND or NAND 
gates to insure communication with the 
correct terminal unit. 

The most difficult task remained: design- 
ing the necessary interrupt logic. It was 
desirable to make the priority of all key- 
boards higher than any of the printers. 
This way, no characters would be lost. 
The inclusion of four terminal drivers 
on a single board forces a significant increase 
in the complexity of the interrupt logic. 

The interrupt logic consists of two 
related sections. The first section required 
properly generating an interrupt from either 
the input or output side of the UART. Fig- 
ure 4 shows the circuit for one side of a 
UART. This circuit appears eight times in 
the completed board. The interrupt enable 
bit must have been set through a 7474 flip 
flop section labeled A in figure 4. Initially, 
the B section of the 7474 is off so the in- 
terrupt request line (INT REQ L) is high 
and not asserted. Likewise, the interrupt 
back line (INT BACK L) is high and not 
asserted. When a character is received (in 
the case of the receiver side of the UART), 
UART DONE causes a low to high level 
transition on the clock input_of the B 
section of the flip flop. Since Q was high, 



D is high and Q is then_asserted, making the 
interrupt request line (Q) active. This signal 
then serves as input to the interrupt arbi- 
tration logic. The interrupt back line (INT 
BACK L) will remain high until the actual 
vectoring takes place. After that, a low to 
high transition on the interrupt back line 
will cause the B section of the 7474 to 
shut off and stay off until either the inter- 
rupt enable or the UART done line is 
cleared and set again. As a convenience, 
any processor write operation to the status 
register will also reset the UART making 
the UART done line wait for the next 
character to be received. 

The interrupt arbitration logic is in 
figure 5. Interrupt requests are arbitrated 
by the 74148 8 line to 3 line priority en- 
coder. With the enable input (El) line 
normally low, the gate status (GS) output 
will go low when at least one of the inputs is 
low, signaling an interrupt request had been 
posted. The outputs of IC6 will be a binary 
encoding of the one's complement of the 
highest priority input signal that is asserted 
low. When the processor acknowledges the 
request, the proper vector information, 
which is made up of a combination of switch 
settings and 74148 outputs, will be put 
onto the bus through the 7438 bus drivers. 
See table 2 for an enumeration of the 
vectoring. Observe that the bus is at ground 
potential for an address bit of 1 . At the same 
time, the D3 input to IC7 will go low assert- 
ing an output line corresponding to the 
interrupt. When the interrupt sequence is 
done, the D3 input goes high and the cor- 



122 February 1980 © BYTE Publications Inc 

















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32K Board Pictured Above 



Why Not the Best? 

From The Dynamic RAM Company. 



2MHz 


4MHz 


16K— $249 


$259 


32K— $375 


$395 


48K— $500 


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64K— $625 


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We have now been shipping 
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assembled, tested, and guaranteed 
for a full year at the price we do. 

Circle 75 on inquiry card. 



Deselect around PROMs. Our 

boards have the important deselect 
feature which lets you overlap any 
fixed memory in your system with 
no interference. 

Our features make the board 
easily used and expanded. You 
address our boards on 1 6K 
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Low power consumption keeps 
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consumption of our 1 6K board is 
typically less than 4 watts ( + 8V @ 
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-16V @ 20ma). Boards with 
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increase power consumption only 
1 watt per 1 6K! 

Standard S-100 Interface. Our 
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Call or write us today. That will 
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also. 

Central Data Corporation, 713 
Edgebrook Drive, PO Box 2530, 
Station A, Champaign, IL 61820. 
(217) 359-8010 

Central Data 

BYTE February 1980 123 



responding interrupt back line goes high 
clearing its respective D flip flop from 
figure 4. Simultaneously, IC8 is triggered to 
time out the gate status output of IC6. This 
is necessary because the remainder of the 
interrupt logic requires the gate status line 
to go high before it can be asserted to 
request another interrupt. 

Unfortunately, there is a period of about 





74148 Output 






Interrupt 


A2 A1 AO 


Octal to 7442 


Vector Offset 


KBDO 


L L L 





+ 


KBD 1 


L L H 


1 


+10 


KBD2 


L H L 


2 


+20 


KBD 3 


L H H 


3 


+30 


PRINTO 


H L L 


4 


+ 4 


PRINT 1 


H L H 


5 


+14 


PRINT 2 


H H L 


6 


+24 


PRINT 3 


H H H 


7 


+34 



Table 2: Vector table generated by the 74148 and 7442 (ICI and IC2 in 
figure 5) combination through the bus drivers. 



50 to 100 ns when the bus drivers are active 
that a higher priority interrupt could per- 
haps sneak through IC6 and deskew the 
correct data. This problem could probably 
be eliminated by giving the higher communi- 
cation rate terminals a higher priority or by 
using an extra set of latches. 

If all the UARTs were driven off the same 
clock source, the interrupts could only occur 
simultaneously (in which case the arbitration 
works correctly) or at least spread apart by 
an interval equal in length to 16 times the 
transmission rate. This would be 26 /us at 
2400 bps. Feeling that the odds of two 
people typing two keys within 100 jus of 
each other is quite small, the circuit re- 
mains as presented. The interrupt enable 
bits and the done flags are reported back to 
the user through 74153s, dual 4 line to 
1 line data selectors. The input to these 
chips comes from the interrupt enable 
signals of the 7474s and from the UARTs 
directly. 



INTERRUPT 
LINES 




i INTERRUPT 
} BACK 
LINES 



O INTERRUPT REQUEST LINE 



BUS D07 LINE 

BUS D06 LINE 

BUS 005 LINE 

BUS D04 LINE 

BUS D03 LINE 

BUS D02 LINE 

BUS INTERRUPT SEQUENCE LINE 



<zt> 



-< I GRANT INTERRUPT 



Figure 5: The interrupt arbitration logic interfaces the requests from the UARTs to the re- 
mainder of the bus interrupt sequence logic. Note that the 74148s can be wired in serial to con- 
trol even more requests. 



124 February 1980 © BYTE Publications lnc 



An additional item: in trying to keep my 
costs to a minimum, my clock driver con- 
sisted of an NE556 dual timer and a 7493 
divide by 16 counter instead of a MC1441 1 
bit rate generator. Luckily, the NE556 was 
the only part not in my rather well stocked 
junk box at the start of this effort. The 
clock circuit is shown in figure 6. Current 
market price for four terminal interface 
boards for the PDP-11 is about $1600. 
This interface required some four months 
of spare time to design and debug. The 
time has been well worth the effort. My 
20 mA teleprinter, operating at 110 bps, 
and my EIA modem, operating at 300 bps, 
are currently attached to this interface with 
two ports still open. Now I have a single 
terminal interface left over with no use 
for it. I guess I will have to find another 
terminal." 

BIBLIOGRAPHY 

1. PDP-11 Peripherals Handbook, Digital Equip- 
ment Corp, Maynard MA, published yearly. 

2. Signetics Logic Data Manual, Signetics Corp, 
Sunnyvale CA, published yearly. 



m 



A7 



ICI I 

RESET NE556 VCC 

DISCHARGE RESET 

THRESHOLD DISCHARGE 

TRIGGER THRESHOLD 

OUTPUT TRIGGER 

GROUND OUTPUT 



Figure 6: This simple 
clock circuit will drive 
the UA R Ts at any reason- 
able speed between 110 
bps and 2400 bps. The 
resistance values are ap- 
proximate. Pin 9 on the 
NE556 is adjusted for 
26 ijls and pin 5 is ad- 
justed for 5 70 ijs. 



OI/iF 




OUTPUT(BPS) 
LZ>"° 



O>l50 
O>300 
■L3>600 
CZ> IHOO 



-d>2400 




Compiler executes under the CP/M operating system 

in as little as 32K bytes of RAM. 

Interactive Symbolic Debugger which enables the 

programmer to examine variables, set a breakpoint, 

and trace procedure calls interactively at run time. 

Pascal/MT® compiles at the rate of 600 lines per 

minute on a 2 MHZ 8080. 

Programs Execute up to 10 TIMES FASTER than 

popular interpretive Pascals. 

The code generated is 8080 object code which is 

ROMable with a minimum run time overhead of 1.5K 

bytes. 

Interrupt procedures allows the programmer to write 

interrupt drivers for I/O and other real time tasks in 

Pascal/MT. 

Bit manipulations of variables may be preformed with 

the built-in procedures: SETBIT, CLRBIT, TSTBIT, 

SHL, SHR, SWAP, L0, HI. 



Memory, Input and Output ports may be directly 

accessed from Pascal/MT. 

Assembly language subroutines may be called from 

Pascal/MT. 

Software floating point, is standard, in addition, this 

package is compatible with the AMD9511 hardware 

floating. 

AMD9511 hardware floating point drivers are 

available with the purchase of the run time package 

source library. 

Business arithmetic version of Pascal/MT is also 

available. This package supports an 1 8 digit BCD with 

4 fixed decimal places. 

Pascal data structures supported are: ENUMERATION 

AND SUBRANGE TYPES, RECORD, ARRAY, REAL, 

INTEGER, CHAR, and BOOLEAN. 

Not implemented are: SETS, GOTO, GET, PUT. 



FMG CORPORATION 

P.O. Box 16020 

Fort Worth, Texas 76133 

[817] 294-2510 

CP/M is a trade name of Digital Research. 
' Pascal/MT is a trademark of MT MicroSYSTEMS. 



AVAILABLE FROM 

MT MicroSYSTEMS 

8672 I Via Mallorca 

La Jolla. Ca. 92037 

[714] 223-5566 ext 289 



Lifeboat Associates 

2248 Broadway 

New York, N.Y. 10024 

[212] 580-0082 



Circle 76 on inquiry card. 



February 1980 © BYTE Publicalions Inc 125 



NEECO 

PROUDLY 

ANNOUNCES 



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02194 (617)449-1760 



Microcomputer Systems Division 
Circle 77 on inquiry card. 



Telex: 951021 



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Circle 72 on inquiry card. 




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BYTE February 1980 127 



Comparison of Some 
High-Level Languages 



Robert A Morris 

Associate Professor 

Department of Mathematics 

University of Massachusetts 

at Boston 

Boston MA 02125 



Different languages are 
appropriate for different 
tasks: multilingual ability 
is as useful in the com- 
puter world as it is in 
the human world. 



The time is not far off when microproc- 
essor users will begin the serious use of high 
level languages other than the BASIC sup- 
plied for many current machines. There are 
many projects hither and yon to implement 
contemporary languages in microcomputer 
form, and the emergence of 16 bit proc- 
essors will probably accelerate this trend. 
Indeed, even now microcomputer users have 
a practical way to use high level languages: 
using the personal computer as an intelli- 
gent interactive editing terminal and sending 
source code over telephone lines to be com- 
piled and executed by a large remote time- 
sharing computer. For many such tasks, the 
connection time (the charge levied by the 
big computer operators for merely listening 
to your terminal) is a substantial fraction 
of the total cost. But this lime is short 
compared to the data entry time, which 
will be entirely on the user's own system. 

Unfortunately, most information about 
languages is gleaned from people who have 
a stake in a particular language due to a 
greater familiarity with it. Different lan- 
guages are appropriate for different tasks. 
Multilingual ability is as useful in the com- 
puter world as it is in the human world. 
To this end I would like to describe the 
differences and similarities between major 
general purpose programming languages, and 
offer opinions about how these differences 
might affect your choice of a high level 
language. 

A number of the conclusions I draw can 
be attributed to questions of style, and 
many whose personal programming styles 
are different might take issue or even 
umbrage at what I offer. Nevertheless, I 
claim the critical reviewer's prerogative to 
offer opinion, and hope only that it is 
clearly identified. One precaution to the 
novice and to the initiate: In comparing 
programming languages, I assume that 
the specific choices are equally well 
implemented. Unquestionably the worst 



version of language A may be far harder 
to use than the best version of language B, 
even if in principle the opposite is the case. 

My own particular bias is that I am not 
interested in "number crunching": that is, 
the use of the computer for scientific or 
statistical calculations which are complex, 
lengthy (in terms of machine time), and 
which often run repeatedly with different 
data. For such so called production pro- 
grams the programming expense is usually 
small compared with the computing ex- 
pense, and there is a premium on efficient 
programs. Suppose one writes a program 
to solve a system of linear equations by 
Gauss' method with the principal intention 
of understanding that method. It then 
becomes irrelevant that an additional 10 
hours of programming effort can produce 
a 50 percent increase in running speed. 
The program will run only a few times for 
a few seconds. 

Finally, I admit I am a mathematician. 
Mathematicians think in unusual ways, 
especially about computers. I once baf- 
fled a computer professional when I told 
him that most of the programs I write, once 
written and correct, never needed to be 
run. Programming as a logical and esthetic 
discipline is not a very comfortable idea 
to many professionals. In any case, writing 
a program in order to understand an algo- 
rithm, instead of vice versa, is a commend- 
able use of computers and one which colors 
my own thinking. 

In many organizations some system of 
phantom money is in effect for computer 
use. The users and their departments often 
have budgets but do not spend any money. 
Rather they simply have some restriction 
put on their use if this budget is expended. 
Indeed it has been argued that certain com- 
puter use, like library use, should be com- 
pletely without accounting. Nevertheless, 
it is common to talk of one or another 
solution being expensive, and this is to 



128 February 1980 © BYTE Publications Inc. 



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BYTE February 1930 129 




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be understood as being a vague and relative 
term, taking into account such factors as 
computing charges, programmer's time and 
storage charges for data and programs in or 
outside the machine. 

I will discuss essentially three languages: 
BASIC, FORTRAN, and ALGOL (together 
with PL/I). I'll also take a cursory look at 
Pascal and give a brief description of APL 
together with the reasons for not including 
it in this survey. These languages are fairly 
standardized so that if one has learned them 
on one machine, there is very little relearn- 
ing necessary for another. Indeed, aside 
from minor punctuation differences, one 
rarely encounters machine dependent 
features of these languages except for input 
and output (10). Thus it is often practical 
to transport programs from one machine to 
another with very little rewriting except 
for the 10, but in some circumstances this 
can be substantial. 

Many BYTE readers know BASIC al- 
ready, but I will describe it so that a broader 
audience might be reached. In some of the 
following examples I have abused program- 
ming language punctuation in the interest of 
comprehensibility. 

BASIC 

BASIC is an acronym for Beginner's All- 
purpose Symbolic Instruction Code. It was 
developed originally at Dartmouth Univer- 
sity and designed as a conversational inter- 
active language, meaning that the user is 
essentially in immediate and constant con- 
tact with the computer. A good BASIC 
translator will give some diagnostic messages 
even as the user types in the program. In 
any case the system will attempt to indicate 
to the user the point at which a linguistic 
error occurs. This is true for most high level 
languages whether conversational or not, but 
the conversational feature and the similarity 
of BASIC to ordinary mathematical notation 
make it a particularly easy language to learn 
and use. In fact, it is the language of choice 
when the program to be written is short, 
say 20 commands or less, and the manipula- 
tion no more than high school algebra. 
BASIC is typically available on the inter- 
active minicomputers used in many high 
schools. It looks like this: 

100 LETX=Y=3 

200 LET Z=5 

300 LETW=3*(X+(Y/2)) 

400 PRINTW 

500 END 

BASIC is an inherently expensive lan- 
guage in terms of time, because it is inter- 
preted rather than compiled. This means 
that the program is translated into machine 



130 February 1980 © BYTE Publications Inc 



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BYTE February 1980 131 



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language each time it is executed, rather 
than translated once and stored in machine 
form. The technical differences between 
interpreters and compilers are not otherwise 
relevant here. Roughly speaking, with an 
interpreter one does much less cajoling of 
the computer to get it to pay attention to 
one's program. 

BASIC programs are easy to alter. To 
change a line, simply retype the offending 
line number followed by the new text, 
then a carriage return. The new line replaces 
the old and one can try to execute again. 
Thus, getting a program working right can 
involve very little waiting. 

Many large computers operate in batch 
mode. This means that the user submits the 
program to the operator, typically on 
punched cards, and waits for it to be proc- 
essed in turn. In such an environment the 
interactive feature is of no use. Although 
some batch systems have BASIC processors, 
it seems pointless to use the language this 
way. 

For complicated problems, especially of a 
mathematical nature, BASIC has some 
severe deficiencies, even though it is prob- 
ably the best first language to learn where it 
is available. One of the biggest of these is the 
difficulty of writing a BASIC program in 
pieces. "Passing parameters" can be a very 
messy business in BASIC and it is usually 
important to make sure that there is no 
confusion over the names of the variables. 
Generally, different variables must have 
different names, and the same variables the 
same name throughout a program. Fully- 
implemented FORTRAN avoids these pit- 
falls (in a somewhat unnatural fashion), and 
in ALGOL and PL/I they cannot arise at all. 
The mathematician's penchant for calling 
all independent variables t or x may be 
freely indulged in ALGOL, cautiously so in 
FORTRAN, and not at all in BASIC. This is 
particularly important when one is writing 
general routines to be plugged into several 
programs which may not have even been 
conceived yet. 

FORTRAN 

FORTRAN looks like this: 

l=2 
J=3 
K=l+J 

WRITE(6,10) K 
10 FORMAT(H) 

The write statement, if mysterious, is at 
least formal and standard. It instructs the 
machine to write on output unit 6, probably 
a printer or the user's terminal, according to 
format statement 10, the present value of 
the variable K. 



132 February 1980 © BYTE Publications Inc 



Circle 82 on inquiry card. 



Circle 83 on inquiry card. 



Respectable modern FORTRAN com- 
pilers allow the programmer the option of 
ignoring the format and outputting the 
results in some standard fashion. 

FORTRAN stands for FORmula 
TRANslator. It is the oldest and most 
widely used language for scientific com- 
puting. FORTRAN compilers for most 
machines produce extremely efficient 
machine language programs because demand 
is so great and the language has such a long 
history. For this reason, also, there are 
many compilers with excellent diagnostic 
features, such as the University of Waterloo's 
WATFOR and WATFIV systems available 
for large IBM machines and even optimizing 
compilers which attempt to improve on the 
programmer's efforts. 

However, as we shall see, some of the 
classic features of FORTRAN are the very 
ones that should make people shun it. But 
because it is so familiar, it is difficult to 
convince FORTRAN adherents that the 
language is detrimental to their efforts. Of 
course, for production programs, efficiency 
is a legitimate reason to use it. Writers of 
more ephemeral programs should be aware 
of the extent to which the other languages 
around them are being improved and be sure 
the sacrifices are needed. There are two 
major objections to FORTRAN: it is diffi- 
cult to write readable programs; and it is 
difficult to structure programs in a logical 
way that reflects the programmer's mathe- 
matical ideas for the solution of the given 
problem. I do not claim that these tasks 
are impossible. But it is widely agreed that 
typical FORTRAN programs are unreadable. 
This is often caused by bad habits encour- 
aged by the language. A common experience 
with large FORTRAN programs is that some 
months after writing one, even the program's 
writer must study it at length to find out 
how it works. For another reader, this job 
may be immense. 

One of the main reasons for this is the 
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may contain a statement such as IF (condition 
to be tested) THEN GO TO 55. If the Condition 
is not met, the computer executes the next 
instruction, but if it is met it executes the 
series of instructions which begins with 



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February 1980 © BYTE Publications Inc 133 



statement number 55. However, people 
never think in this way even if the alterna- 
tive courses of action are too complicated 
to remember in detail. Instead of bearing in 
mind where the alternatives may be found, 
one always keeps in mind what they are, 
perhaps in some brief mnemonic form. Thus 
the ALGOL statement: 

IF GCD(A,B)^1 THEN 

P:=SMALLEST.COMMON.PRIIvlE.DIVISOR(A,B) 
ELSE 

P:=MIN(A,B) 

is surely more informative than the 
FORTRAN version: 

IF (GCD(A,B).NE.D THEN GO TO 55 

P=MIN(A,B) 

GO TO 65 
55. . . .code describing how to find smallest 
common prime 
65 continuation of program 

I am not suggesting that ALGOL knows 
how to find the smallest common prime. Of 
course, the words smallest.common. 
PRIME. DIVISOR(a.B) must also be defined in 
the program, just as they would at line 55 
in the FORTRAN program. But the 
FORTRAN programmer, in the interest of 
intelligibility, must add comments, both at 
line 55 and at the appeal to it, telling the 
reader what is going on. The necessity of 
adding comments (words which explain the 
program to the reader but which are ignored 
by the computer) is a sign that the conven- 
tions of human thought have been sacrificed 
to the conventions of the programming 
language. This is a common occurrence in 
FORTRAN and almost impossible to avoid 
with the use of GOTO statements (see refer- 
ence 6 for an exposition of this point and 
its history). 

The second mathematical objection to 
FORTRAN is that dummy variables are 
somewhat restricted. They occur auto- 
matically in subprograms (small portions of 
a program which are executed repeatedly 
but each time with different values assigned 
to their parameters), but otherwise are 
essentially absent. This means that some care 
must be taken in writing complicated pro- 
grams so that variable names are not con- 
fused. Because of this it is difficult to 
transport pieces from one program to 
another. A skilled FORTRAN programmer 
told me that his biggest headache is having 
to constantly rewrite the same algorithm. 
That favorite phrase of mathematicians 
"we are done because we are reduced to a 
previously solved case" is very difficult 
to put in practice in FORTRAN and 
BASIC but quite easy in ALGOL and PL/I. 
FORTRAN subprograms are not recursive. 



That is, unlike their ALGOL counterparts, 
they cannot appeal to themselves in their 
own definition. This subtle difference can 
have extreme consequences in nonnumeric 
calculations, but this is beyond our scope. 

ALGOL-like Languages 

ALGOL is the ALGOrithmic Language 
developed around 1960 (a standard and 
quite commonly available version is called 
ALGOL 60). Originally intended as a lan- 
guage for specifying algorithms for publica- 
tion, it is now widely implemented and 
used in scientific environments, especially 
in Europe. A portion of the language PL/I 
is similar to ALGOL, and the remarks below 
generally apply to it. Since PL/I is supported 
by IBM for its machines far more than is 
ALGOL, users of IBM equipment may prefer 
to keep it in mind. Pascal is a kind of second 
generation ALGOL 60 to which most of the 
comments in this section apply. 

Simple ALGOL appears much like BASIC: 

BEGIN 

INTEGER X,Y,Z; 

X:=3; Y:=2; Z:=X+Y; PRINT(Z); 
END. 

This program does what the BASIC example 
does. The differences are in punctuation. 
ALGOL commands are separated by semi- 
colons, whereas BASIC requires each to have 
a line number. ALGOL uses the symbol ■- 
to assign a value to a variable while BASIC 
requires the theme let X=3 (though some 
versions make LET optional). 

Most notable is that the type of each 
variable must be specified; in this example 
each variable is declared to be an integer. 
In BASIC no distinction is made between 
integers and real numbers, while in 
FORTRAN, if a variable name begins with 
(usually) l,J,K,L,M or N it is understood to 
be an integer. Otherwise it is a real variable 
with some understood accuracy convention 
(complex variables are also allowed in 
FORTRAN and most ALGOL implementa- 
tions). These conventions can be overridden 
by the programmer, and readability need not 
be sacrificed in FORTRAN. 

One main feature of ALGOL which 
makes it attractive for mathematical and 
logical problems is that it \sablock structured 
language. By definition a block is a piece of 
code that begins with BEGIN and ends with 
END. There may be blocks within blocks 
nested as deeply as physical limits imposed 
by the actual computer will allow. Within 
each block one may declare the names of 
variables which are to exist only within that 
block. These variables do not have any 
existence outside that block and indeed, 



134 February 1980 © BYTE Publications Inc 



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outside the block there may be other vari- 
ables with the same name and they will not 
be confused. Consider the following program: 

BEGIN 

INTEGER X,Y; 

X:=3;Y:=2; 

BEGIN 

INTEGER X,Z; 

X:=6;Z:=X+Y; PRINT(X);PRINT(Z); 
END; 

PRINT(X); 
END. 

The variable X in the inner block bears 
no relation to the X in the outer block and 
references to it in the inner block behave as 
though there were no X in the outer block. 
The Y in the inner block, however, has not 
been declared there, so it refers to the next 
most global occurrence of Y: namely that in 
the outer block. This program will output: 

68 3 

The first two numbers are produced by the 
print statements in the inner block, the last 
by that in the outer block. 

This example is a trivial illustration, but 
the reader will appreciate that no care 
whatsoever need be taken with the naming 
of those variables whose existence is not 
needed outside the algorithm of which they 
are part. For this reason, algorithms are 
easily transported from one program to 
another. The possible sources of confusion 
arising from these so called local variables 
are approximately the same as those arising 
in ordinary mathematical discourse: "the 
variable x here is not the same as the variable 
x in the previous section." 

Another feature of ALGOL and PL/I 
that adds to the ease of structuring programs 
is the existence of condition testing phrases 
other than IF. For example, one may use the 
sequence WHILE . . . condition to be tested. . . 
DO. .. something. Not only is this close to 
our way of thinking, but it has surprising 
implications for the programming solutions 
which are naturally suggested by the lan- 
guage. Such structures have been urged for 
FORTRAN and may well be included in 
future versions. They are beginning to 
appear in nonstandard versions of FORTRAN 
already. 

What are the disadvantages of ALGOL? 
Foremost is that even the most commonly 
used mathematical procedures are often not 
preprogrammed into the system as they are 
in BASIC and FORTRAN. Thus, although 
arrays are a standard data type in ALGOL, 
there are no matrix manipulation functions 
such as BASIC'S LET MAT A = B + C. The 
programmer is responsible for adding the 
routines to perform these operations. 
Because of the transportability we have 



136 February 1980 © BYTE Publications Inc 



discussed, this is not particularly difficult. 
In many systems, these routines could be 
stored on a high speed storage device such as 
a magnetic disk, easing the task even further. 
Thus, each programmer or group may have 
to build a library of standard routines, 
whereas in BASIC and FORTRAN large 
libraries are usually already provided. 

These functions often include many 
transcendental functions and sophisticated 
procedures, but ALGOL libraries may 
contain little more than elementary func- 
tions. This is largely a historical development 
and may be expected to change as ALGOL 
becomes more widely used. This drawback is 
of little consequence if one's application is 
nonnumeric. At this writing I am program- 
ming procedures in ALGOL to calculate 
with polynomials over finite fields. Since it 
is too much to expect any library to have a 
routine to calculate the zeta function of a 
curve, I am not terribly restricted by the 
skimpy offerings of ALGOL libraries. 

Even more consequential, because of its 
limited libraries, is the fact that ALGOL 
tends to require more programming effort 
for 10 than FORTRAN or BASIC. Simply 
getting numbers in and out is generally easy, 
but adjusting format or 10 of text may be 
a complicated task. 10 is at least standard- 
ized, if cumbersome, in FORTRAN and 
BASIC. However, 10 is not part of the 
official definition of ALGOL, which burdens 
it with machine dependent features. 

Pascal 

Pascal is a modern language derived from 
ALGOL 60 that addresses itself to a very 
important issue we have not dealt with so far 
in this elementary exposition: data struc- 
tures. 

Pascal allows the user to define and 
manipulate new types of data beyond the 
fundamental types (integers, reals, arrays, 
strings) which appear in the older languages. 
Further, it does so in a completely recursive 
fashion, which adds considerable power to 
this feature. These matters are beyond the 
scope of this article, but, as designed, Pascal 
is easy to learn, powerful and very much like 
ALGOL in nature. 

APL 

APL stands for A Programming Language. 
It is a high powered language designed to 
make the handling of matrices and vectors 
particularly easy, and as such it is very 
successful. Its adherents tend to be emphatic 
about its value as a general purpose language. 
My own view is that its array orientation is a 
disadvantage for structuring complicated 



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programs unrelated to array handling. The 
language does not encourage the writing of 
readable programs. It is easy and tempting to 
write very compact, cryptic programs 
(however, this is a human decision and not 
really forced by the language). The present 
view of programming languages is that the 
elementary data and control structures of 
the language shape the programmer's way of 
thinking about solutions. Because of its 
underlying array orientation, I prefer to put 
APL with special purpose languages and 
omit it from this discussion, even though it 
is so widely used that it can not be regarded 
as an exotic language. 

Exotic Languages 

A number of special purpose languages 
and systems have arisen as the result of 
research in computer languages. An annual 
survey of languages is published by the 
Association for Computing Machinery. 

Some of these special purpose languages, 
like the algebraic manipulation systems, may 
be particularly complex or difficult to use, 
although appealing to the mathematically 



inclined. Others, while exciting in prospect, 
are only beginning to be implemented. 
Anyone wishing to explore these languages 
should first gain some traditional program- 
ming skill and establish a close relationship 
with the professionals at the computer center 
where you are using them, because the 
exotic products do not always behave 
as promised and sometimes need a little 
coaxing from the systems programmers. 

Acknowledgements 

None of the ideas expressed here is 
original. They have been percolating in the 
computer field for a few years, but appar- 
ently are still regarded by some as controver- 
sial. The names often associated with them 
are Dijkstra, Wirth, Knuth and Hoare, whose 
works set them out in detail. I thank Richard 
Palais for nudging me toward ALGOL and 
thence to a consideration of these ideas. 
I wrote this article using a computerized 
text formatter adapted from the 
RATFORMATter of Kemighan and Plaugher 
(see bibliography) who were the first to 
insist that there is such a thing as literacy in 
programming. 



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138 February 1980 © BYTE Publications Inc 



Circle 90 on inquiry card. 



Getting Started 

The bibliography which follows contains 
my own favorite introductory texts. Consult 
local opinion also, because personal explana- 
tion is one of the most useful tools in 
learning programming. If a particular book is 
highly regarded by people around you, 
your questions may be more easily answered 
by others familiar with it. Two other 
warnings are necessary: you cannot under- 
stand programming without writing and 
running programs; and be wary of the 
machine manufacturer's language manuals — 
they are often written for someone who 
already knows the language or some other 
high level language. But check them for 
minor differences with your text. With 
ALGOL you will probably have to learn the 
10 from the manual." 



10. 



Science, number 184, May 31 1974, pages 
957 thru 961. 

McCracken, D D, A Guide to ALGOL Pro- 
gramming, Wiley, Somerset l\IJ. The problem 
with this and other ALGOL primers familiar 
to me is that they don't really discuss the 
features of ALGOL that make it powerful. 
But it is fine for getting started. 

McCracken, D D, A Guide to FORTRAN IV 
Programming, Wiley, 1972. A widely used 
text. Included are excellent discussions on 
points of style and efficiency, and an ap- 
pendix on the WATFOR and WATFIV 
compiler. They are often used at universities 
running IBM systems. They will ease the 
learning of FORTRAN, as will this book. 

Weinberg, G M, PL/I Programming: A Manual 
of Style, McGraw Hill, New York, 1970. Yet 
another beginning. 



1 1 . Wirth, N, Systematic Programming: An Intro- 
duction, Prentice-Hall, Englewood Cliffs NJ, 
1973. 



BIBLIOGRAPHY 

1 . Kernighan, B and Plaugher, P, Software 
Tools, Addison-Wesley, Reading MA, 1976. 

2. Dahl, J, Dijkstra, E W, and Hoare, C A, 
Structured Programming, Academic Press, 
New York, 1972. 

3. Floyd, R W, Introduction to Programming 
and the ALGOL W Language, Department 
of Computer Science, Stanford University. 
ALGOL W is an extension of ALGOL 60 
written at Stanford for the IBM 360, and if 
you have it, you'll find this book particu- 
larly useful. If you are adventuresome, 
consider using it anyway, using the machine 
manufacturer's manual to sort out the dif- 
ferences. Like McCracken, it's just a 
beginning. 

4. Jensen, K and Wirth, N, Pascal User Manual 
and Report, second edition, Springer-Verlag, 
New York, 1974. Not a programming primer, 
but definitely a Pascal primer. A small 
amount of any programming experience 
will suffice to read it (an all too brief intro- 
duction attempts to substitute for this ex- 
perience). It also contains the "Report," 
the official definition of Pascal, which may 
prove interesting to those who have never 
seen such a document. 

5. Kemeny, J G, and Kurtz, T E, BASIC Pro- 
gramming, Wiley, Somerset NJ, 1971. By 
the fathers of BASIC. 

6. Knuth, D E, and Wirth, N,ACM Computing 
Surveys, volume 6, number 4, 1974. Special 
issue on programming with articles by these 
two authors and others. 

7. Luehmann, A W, and Nevison, J M, "Com- 
puter Use Under a Free Access Policy," 



Also see Communications of the 
volume 19, number 12, 1976. 



ACM, 



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February 1980 © BYTE Publications Inc 139 



Technical Fcpum 



Some Example Plots 



David Dameron 402 E OTCeefe St, Apt 27, E Palo Alto CA 94303 



I have been reading BYTE since it was first published in 
1975 and have enjoyed its articles, especially those on 
plotting graphics. My computer is a Cromemco Z80 with 
48 K bytes of programmable memory and a 5-inch disk 
drive. This configuration gives about 20 K bytes of 
available user memory with 16 K BASIC. My plotter is a 
Sylvanhills DFT-2, run from a parallel port. I modified 
the plotter to use stepping-motor X,Y movements, under 
computer control after reading "Taking the First Step" 
(February 1978 BYTE, page 35). It now has 300 points per 
inch of resolution using 15-degree stepping motors. 

After the basic vector control software was completed, 
one of the first routines I entered was a character 
generator: "A Plot is Incomplete Without Characters" 
(July 1976 BYTE, page 64). Inspired by "Venus de Plotto" 



(February 1977 BYTE, cover), I entered various three- 
dimensional routines, for example: "Hidden Line 
Subroutines for Three-Dimensional Plotting" (May 1978 
BYTE, page 49). You can see that BYTE has greatly con- 
tributed to this plotting system. 

The three-dimensional plot "Waves" (figure 1) is an ex- 
ample of the hidden line routines. There are 141 points in 
the X direction and 156 in the Y direction. It is the sum of 
four radially-damped sinusoidal waves rotated in three 
dimensions. The program took about 10 hours to run 
with a 4 MHz clock, divided evenly between point 
calculation and the actual plotting, which was done con- 
currently. Listing 1 is a chord program which produces 
the output in figure 2 (page 144). 

This sample output took about 90 minutes to plot; a 















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Figure 1: Three-dimensional wave program output which took 10 hours to produce. 

140 February 1980 © BYTE Publications Inc 



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CP-52 Cable Panel - Terminates two 26-conductor flat cables in 26 screwlugs. Use it for convenient interconnection of the 1 00-EMM 
to the "outside world". $45.00 

CABL-26-STD 26-Conductor Flat Ribbon Cable - Four feet in length with connectors for 1 00-EMM and CP-52 above. $35.00 Other 
lengths available on special order. Add $1.00 per foot. 

OTHER PRODUCTS FROM IDS. The most complete source of S-1 00 compatible modules for process con- 
trol, data acquisition, energy management, and data communications. 

88-MODEM S-100 ORIGINATE/ANSWER MODEM WITH AUTO- 
DIALER. Software selectable baudrate provides any baudrate from 66- 
600 baud. Provides 1 .5 stop bits when operated in 5-bit code mode. 
Auto-answer programs available for CROMEMCO CDOS, CP/M, North 
Star Horizon and MDS, and Alpha Micro. 

Assembled and Tested $395.00 Kit $245.00 




88-UFC UNIVERSAL FREQUENCY COUNTER 

Four software selected inputs. Measure frequency from O-650 
MHz and period from .luS to 1 Second. Extensive software in- 
cluded. 

Assembled and Tested $299.00 Kit $199.00 Temperature- 
Compensated Crystal Oscillator option $145.00 

88-SAI SYNCHRONOUS/ ASYNCHRONOUS INTERFACE 

The most versatile serial interface on the market. Computer ac- 
cess/control of all data and handshake lines and provision for 
masked interrupts, inversion of any input or output signal, and 
onboard baudrate generation for 110, 134.5, 150, 300, 600, 
1200, 2400, 4800, 9600, and many other baud rates. Many 
more features. 

Assembled and Tested $299.00 Kit $199.00 



88-SPM TIME OF DAY CLOCK with battery backup. Set the 
clock with three out instructions: no delays! Programs included 
in North Star BASIC, CBASIC, and 8080 assembly language. 

Assembled and Tested with crystal option $199.00 Kit less 
crystal option $99.00 Crystal Option Kit $25.00 

88-RCB RELAY CONTROL BOARD 

16 Relays on one board. Control appliances, production equip- 
ment, or even musical instruments (See BYTE Magazine Sept 
1977 page 12) 

Assembled and Tested $299.00 Kit $199.00 



INTERNATIONAL 
DATA SYSTEMS, INC. 



Mailing Address: 

Post Office Box 17269 
Dulles International Airport 
Washington, DC 20041 

Telephone (703)661-8442 



Shipping Address: 

400 West Service Road, Suite 130 
Dulles International Airport 
Washington, DC 20041 USA 

TELEX 901112 IDS CTLY 



Circle 92 on inquiry card. 



BYTE February 1980 141 



10 


REM DRAWS PLL CHORDS WITHIN HN N- 


GON 7/16/76 


240 


U2=l : F=l 




20 


REM USES DIMENSIONS IN PLOTTER RRSTERS 


250 


N1=N 




30 


REM WRITTEN BY DRV ID H. DRMERON 




260 


IF I=N/2 THEN N1=I 




40 


REM INITIALIZE PLOTTER HERE. 




270 


REM J1=FR0M, J2=T0 POINT 




50 


INPUT "NUMBER OF SIDES? ",N 




280 


REM MAKE J1=PREVI0US J2 UNLESS 


TAKEN (H(J1)=1) 


60 


DIM BCN),C(N) 




290 


REM IF TAKEN INCREMENT Jl TILL 


1 FOUND, LIFT PEN 


70 


INTEGER I,J,H(N) 




300 


FOR J=l TO Nl 




80 


INPUT'RPDIUS OF PLOT? ",R 




310 


U1=U2 




90 


Pl=6.2831853/N 




320 


IF H(J1)=0 THEN 360 




100 


FOR 1=1 TO N 




330 


J1=J1+1 : IF J1>N THEN J1=U1-N 


110 


B( I )=R+10+R*C0S( ( 1-1 )*P1 ) 




340 


F=l 




120 


C( I )=R+10+R*SIN< ( 1-1 )XP1 ) 




350 


GOTO 320 




130 


NEXT I 




360 


J2=U1+I 




140 


FOR 1=1 TO INTCN/2) 




370 


IF U2>N THEN J2=J2-N 




150 


REM DRAW LINES TO I'TH NEIGHBOR 




380 


H(J1)=1 




160 


FOR J=l TO N 




390 


REM F=l IS A FLAG TO LIFT THE 


PEN 


no 


H(J)=0 




400 


REM IF F=l THEN MOVE TO B(J1) 


C(J1) WITH PEN LIFTED 


180 


NEXT J 




410 


REM CALL VECTOR ROUTINE HERE. 




190 


IF I <>N/ 2 THEN 240 




420 


F=0 




200 


REM DRAW ONLY 1/2 LINES IF DIAMETERS 


430 


REM DRAW TO B(J2),C(J2) HERE. 


INSERT VECTOR ROUTINE HERE. 


210 


FOR J=N/2+l TO N 




440 


NEXT J 




220 


H(J)=1 




450 


NEXT I 




230 


NEXT U 




460 


STOP 





Listing 1: Program Chord produces a series of chords for a given circle. The sample output is shown in figure 2 (page 144). This listing 
was made hy the author's system using a plotter. 



little backlash can be seen at the vertices of the 29-sided 
polygon. The listing was plotted on this system with 
characters four times the minimum size. This routine was 
written to remove some of the unnecessary plotter X,Y 
motion from that of just cycling through all the vertices 
for both the starting and ending points. Plotter routines 
should be inserted at lines 390 and 430 to suit a particular 
system. At 390, move to B(Jl), C(J1) with the pen lifted. 
At 430, draw a line to B(J2), C(J2) with the pen down. 
I use the system in my work plotting graphs and other 



forms of data, and I hope to eventually sell some of the 
computer graphics I have produced. It is stimulating and 
fun to create various plot outputs on the spot, now that 
the hardware has been debugged and is running. The 
plotter output is not limited to ink drawings on paper. A 
needle or other engraving point may be mounted in the 
pen holder (a small clamp) for drawing etching lines in a 
zinc plate through a thin layer of an acid resisting 
substance. The plots can then be etched by dumping the 
plate in an acid bath for an appropriate time period. 



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WE EXPORT TO ALL COUNTRIES OVERSEAS CALLERS USE (212) 448-6298 OR TWX: 710 588 2844 CABLE: OWENS ASSOC. 

We have no reader inquiry number. Please call or write. Product sheets available. 


john d. OWENS ASSOCIATES, inc. 

1 2 SCHUBERT STREET STATEN ISLAND. NEW YORK 1 0305 (21 2) 448-6283 (21 2) 448-6298 



142 February 1980 © BYTE Publications Inc 



Circle 93 on inquiry card. 



A BUSINESS PROPOSITION 

from 

INTE3TEC DATA SYSTEMS 



Dear Computer Enthusiast: 

As a result of the phenomenal growth our company has 
experienced during the past year, there are now many 
excellent opportunities in our national dealership program. 
And as a result of this expansion in our dealership network, 
there are new employment opportunities in the marketing 
and technical divisions of our company. We'd like to talk 
about these opportunities for just a minute. 

Our two major products, the InterTube II Video 
Terminal and the SuperBrain Video Computer are, to say 
the least, an overwhelming success. This widespread 
acceptance and demand for our products naturally requires 
the establishment and maintenance of a comprehensive 
dealer/service network. Many retailers and other 
microcomputer resellers have already joined our team. They 
are now realizing the true advantages our unsurpassed 
price/performance products can give them. How about 
you? Isn't it time you breathed a little new life into your 
operation? Dealership and OEM contracts are now being 
established in many areas. Call us today and discuss your 
requirements. You'll find us to be quite responsive. 

Of course, our ability to successfully penetrate and 
maintain our position in this ever-increasingly competitive 
marketplace is due to the support of our many marketing, 
technical and service personnel. As our marketshare 
increases, so does our requirement for qualified personnel. 
We are presently recruiting marketing representatives to 
work closely with our dealers in the field. A 
sales/management background in this industry would 
qualify you for consideration for one of these positions. 
Also, we are in search of technical personnel to assist us 
here in South Carolina in supporting the varied applications 
our customers have for our products. At present, we are 
recruiting Basic, Fortran and Assembly language pro- 
grammers as well as lab and production technicians. 

Whatever your interests may be, dealership or 
employment, we urge you to carefully consider the 
advantages of association with our company. Pause for just 
a moment and give us a call at 803/798-9100. And if you 
don't believe us, ask the industry experts. They will tell you 
we're on the way to the top! So, why not join us now and 
enjoy the ride. 

Best Regards, 



The Marketing Department 

INTERTEC DATA SYSTEMS CORPORATION 



Dear Intertec, 

Yes, I'm interested! Please call me with more 
information about the opportunities I've checked below. 

□ Dealership Programs 

□ OEM Arrangements 

□ Marketing positions presently available in my area. 

□ Technical Support positions available at the factory 

□ Other (specify) 



If you're interested in dealership or OEM arrangements, 
please send us some detailed information on the nature of 
your present business including: 1) type of business; 2) 
length of time in business; 3) number of employees in sales, 
service and administrative positions; 4) products presently 
represented and/or manufactured, and 5) your application 
for our products. 

If you're interested in employment, whether it be in a field 
marketing position or a technical factory position, please 
enclose a resume detailing your experience and salary 
requirements. 

Don't delay! Give us your name and address below and 
return this advertisement to: 



INTE3TEC DATA SY5TEMS 

The Marketing Department 
2300 Broad River Road 
Columbia, South Carolina 29210 



If you're in a big hurry to reap the benefits of association 
with Intertec, skip the form and call us direct at 
803-798-9100. Just ask for someone in the Marketing 
Department. 

Your name . 



Company. 
Street 



City, State & Zip. 



Telephone 



Circle 94 on inquiry card. 



BYTE February 1980 143 










m 






■\,i 















'.•.>;•• 






^:.^ 



^-•^ 



.'S-S-.'v-s-- 



>•£ 






-a : 






-»t ; 



Figure 2: Sample output of the Chord program written in BASIC. This figure took 90 minutes to produce. 



AGENS 



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The Works. Iterative passes for 
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BONUS: Source link loader file 
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RBB Software Products 



P.O. BOX 21 11 

YORBA LINDA, CALIFORNIA 92686 

(714) 637-5965 



144 February 1980 © BYTE Publications Inc 




How 

COMPUMAX 
stacks up 
to r 

the 
competition 





V sC° ,fi L e a 














^^XOMPARISON SHOPPING? STOP HERE! 


IMPORTANT QUESTIONS 
ABOUT BUSINESS SOFTWARE 


- - 


OSBORNE/ 
McCRAWHILL 


PEACHTREE 
SOFTWARE 


STRUCTURED 
SYSTEMS 


What programs are available? 

Are they INTERACTIVE? 


INTERACTIVE: 
GENERAL LEDCER 
ACCTS PAYABLE 
ACC'TS REC'BLE 
INVENTORY 
PAYROLL/PERSONNEL 


INTERACTIVE: 

CENERAL LEDCER 
ACC'TS PAYABLE 
ACC'TS REC'BLE 

NON-INTERACTIVE: 
PAYROLL 


INTERACTIVE: 

CENERAL LEDCER 
ACC'TS PAYABLE 
ACC'TS REC'BLE 
PAYROLL 

NON-INTERACTIVE: 
INVENTORY 


INTERACTIVE: 

CENERAL LEDGER 
ACC'TS PAYABLE 
ACC'TS REC'BLE 

NON-INTERACTIVE: 
STOCK CONTROL 
INVENTORY 


What versions are available? 


TRS-80, APPLE II 

COMMODORE PET 

MICROSOFT,CBASIC2 CP/M 

MICROPOLIS: 

EXIDY SORCERER, 
VECTOR MZ, DYNABYTE 

CROMEMCOIII 


WANG 
CBASIC2 CP/M 


MICROSOFT CP/M 


CBASIC2 CP/M 


What is the price? 


MICROLEDCER, A/P, 
A/R, INV, PER5: $140.-each. 
MAXILEDCER.A/P, A/R: 
$350. -each. 


CL. A/P, A/R, PAYROLL: 

$250. -each. 
Cost of configuring must 
be added! 


CL, A/P, A/R, PAYROLL, 
INVENTORY$1000each. 


CL$995.- 
A/P$750.- 
A/R$750.- 
INV.$500.- 


Hardware options 


40 column CRT 
64 column CRT 
80 col. terminal 
80 col. printer included 


64 col. CRT only 

132 column printer only 


80 col CRT only 

132 column printer only 


cursor addressable terminal 

only 
132 column printer only. 


Is source code included? 


YES, INCLUDING 
PROGRAM FLOWCHARTS. 


YES 


YES 


NO 


What type of after-purchase 
support is offered? 


1YR WARRANTY* 
CORRECTION OF DEFECTS 

INDIVIDUAL PROGRAM 
AUTHORS AVAILABLE FOR 
QUESTIONS. 


NONE 


1 YR WARRANTY & 
CORRECTION OF DEFECTS 
THROUGH DEALER. 


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FOR QUESTIONS. UPDATES 
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A FEE. 



IS 



yourone-stop shop for all your business bookkeeping software. 



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COMPUMAX software is de- 
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COMPUMAX supplies ready, 
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additional requirements develop. 



Or do as many have done— keep it 
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For a demo, visit your local compu- 
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him give us acall at (415) 321-2881 . 



Circle 95 on inquiry card. 



505 HAMILTON AVENUE PALO ALTO, CA 94301 

BYTE February 1980 145 



Circle 96 on inquiry card. 



Z s - SYSTEMS 



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Technical Fopum 



Introduction to Code 
Tightening 



Geoffrey Gass, 5240 SW Dosch Rd, Portland OR 97201 

"Why should a programmer be so obsessed with pinch- 
ing and scraping to save a few bytes of code?" asks the 
representative from Behemoth Computers Inc. In his part 
of the universe, whether a program takes 110,000 bytes 
or 120,000 bytes is of no particular moment. 

"What a damned tangle!" echoes one of his customers. 
"Haven't they ever heard of top down programming?" 
His part of the computer universe is concerned with pro- 
grams written and understandable by interchangeable 
programmers, so any new job applicant capable of peel- 
ing his own bananas can pick up where the last program- 
mer left off at the time of his unfortunate starvation. 

In a smaller part of the universe occupied by minicom- 
puter users and programmers, "tightening up the code" 
very early became a necessary practice to get useful pro- 
grams into more confined memory spaces. 

An even cozier corner, of course, is that of the personal 
computer programmer, who may have to spend many 
hours in tightening, trimming and squeezing to get a 
couple of quarts of program into his one-quart memory. 

The tightest quarters of all (they might be described as 
"two-by-two by you") are those occupied by the 
microprocessor programmer fitting useful programs and 
modules into read-only memories (ROMs) for dedicated 
systems or monitors. Read-only memories come in 
relatively small, fixed sizes. The first estimate of what can 
be done in a given size read-only memory is always 
excessive of course, but in any typical project the 
absolute hardware limits are set very early, and it's up to 
the programmer to get as many as possible of the 
originally promised features into the fixed module size. 

If by chance there are a couple of no-operation instruc- 
tions (NOPs) in the final coding, then there is immediate 
pressure to do some tightening and squeezing to add 
another feature or two. If, as is more probably the case, 
the first coding runs long, then there is more intense 
pressure to squeeze, pare, tighten and rewrite every con- 
ceivable way to get the program genie into the bottle. 
(Even if the hardware decision is reversed and the read- 
only memory space doubled, program expectations will 
be increased until they again overflow the assigned space. 
This is a corollary of Parkinson's law; it is amply 
verified.) 

The successful programmer in this environment is the 
one who gets the job done. It takes a substantial reper- 
toire of techniques and a good eye for spotting loose 
coding and redundant logic to do a succesful job of fitting 
the required functions into a fixed domain of memory. 
Though he may earn the scorn of the Behemoth man 



FWX 710-985-5485 



146 February 1980 IE) B VI h Publications Inc 



Circle 97 on inquiry card. 



Circle 98 on inquiry card. 



CMPA 


#20 


BMI 


CODIN 


BEQ 


DELIM 


BGT 


TEXTIN 



("cheese-parer!") and the bitter enmity of the user who 
wants to reach in and borrow some of his subroutines, he 
wins in the marketplace when his product does more for 
less money, weight, power or space (or simply gets to the 
market sooner because of fewer hardware redesigns in the 
development cycle). 

The object of this discussion is to present some of the 
tricks of the programmer's trade by which redundant 
logic and loose code can be tightened up to get maximum 
function into minimum memory space. But please heed 
the warning note at the end, lest you get yourself into a 
cleverness box from which there's no escape! 

Redundant logic can be illustrated by the following 
sequence: 

Compare ACCA to the value 20. 
Less than 20? Go to CODIN. 
Equal to 20? Go to DELIM routine. 
Over 20? Treat as text input. 

Obviously, the last instruction is redundant. If the 
accumulator is not less than or equal to 20, it must be 
more than 20, and the third test is unnecessary. Frequent- 
ly, the redundancy is more subtle, being determined by 
external parameters which make certain conditions 
impossible, and therefore unnecessary to test for. 

Loose coding may be illustrated by this nice, 
straightforward top down subroutine for a 6800 string 
print operation: 

PDATA LDAA 0,X Get data byte per index register. 

CMPA #04 Check for EOT (string terminator). 

BEQ EXIT If EOT, return to calling program. 

JSR OUTEEE Not EOT. Output this character. 

INX Step index register to next loca- 
tion. 

BRA PDATA Go back for next byte. 

EXIT RTS Return to calling program. 

The routine uses 13 bytes. The sharp programmer 
notes immediately that it has two branches in it, one of 
them unconditional. An unconditional branch is always 
somewhat suspect in itself; in a short routine already con- 
taining a conditional branch, it's doubly suspect. 

Here's how Wiles and Felix optimized the routine in 
Motorola's MIKBUG read-only memory. By moving the 
entry point to the middle of the routine, the uncondi- 
tional branch can be thrown out and the loop closed by 
the conditional branch alone: 



PDATA2 
PDATA1 



JSR OUTEEE Output the character. 
INX Step to next location. 

LDAA 0,X Enter here. Get character per XR. 

CMPA #04 Check for EOT. 

BNE PDATA2 If not EOT, output the character. 
RTS Was EOT. Return to calling pro- 

gram. 

Now we are down to 11 bytes. To save even more, the 
system could be changed to use 00 (NUL) rather than 04 
(EOT) as the string terminator symbol. Because the N 
and Z bits of the condition code register in the Motorola 
6800 respond automatically to a LOAD operation (this is 
not true of the 8080 and some other processors; you have 
to know the fine print to do a good job of code tighten- 
ing), the comparison can be thrown out: 

PDATA2 JSR OUTEEE Output the character. 

INX Step to next. 

PDATA1 LDAA 0,X Enter here. Get character per XR. 



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STOP PLAYING GAMES 



TRS-80 (Level II) 

PET 

APPLE 

OTHERS 






■ Calculate odds on HORSE RACES with ANY COMPUTER 
using BASIC. 

■ SCIENTIFICALLY DERIVED SYSTEM really works. This 
system was written and used by computer experts and is 
now Pemg made available to home computer owners This 
method is based on storing data trom a large number ot 
races on a high speed, large scale computer 23 taclors 
taken from ihe "Daily Racing Form" were then analyzed by the computer to see how mey in- 
fluenced race results From these 23 factors, ten were found to be the most vital in determining 
winners NUMERICAL PROBABILITIES ol each of these 10 factors were Ihen computed and this 
forms Ihe basis ol this REVOLUTIONARY NEW PROGRAM 

■ SIMPLE TO USE Obtain "Daily Racing Form" the day belore the races and answer the 10 ques- 
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February 1980 © BYTE Publications Inc 147 



Circle 100 on inquiry card. 



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Now, the job is all done in nine bytes, a 30 percent sav- 
ing in code. (This trick could not be used in MIKBUG, 
since some of the strings contained NULs.) 

For the read-only memory programmer, that could 
mean the difference between fitting and not fitting the 
allocated hardware. For the home hacker who hand- 
assembles his code it could be the difference between 
rewriting these few bytes and rewriting several pages of 
code (and risking a blowup if an address or offset is 
overlooked). It's not hard to guess which approach is 
best! 

A Word of Warning 

Here's a word of warning though: if you learn a lot of 
tricks and start applying them all in your original coding, 
there will be nowhere to tighten up if you run over. Your 
coding will also be much harder to understand later when 
you want to do something slightly different with it. 

It's a little pathetic to see a routine loaded with twists, 
kinks, and convoluted logic, followed by a string of 
NOPs, revealing that the programmer was just perform- 
ing logical games for his or her own amusement, or else 
swiped the routine from someone else without understan- 
ding it! 

So, the best programming practice is to go with 
relatively loose and straightforward top down program- 
ming in the initial approach to a problem, and to save the 
tricks until you really need them.B 



Mining the Skip Chain 
for Extra Bytes of Code 

Geoffrey Gass, 5240 SW Dosch Rd, Portland OR 97201 

Need bytes? Go where the code is, and start prospec- 
ting. 

Somewhere, a program will probably be checking a 
value or input against several reference values, perform- 
ing various actions according to the results of com- 
parisons. A common filter construction uses a skip chain, 
a procedure which gobbles up a lot of code. This is 
therefore a good place to start a mine, smelter and 
refinery. 

A typical skip chain might look like this (coding is for 
the Motorola 6800, but the process is essentially the same 
for all machines): 

CTRL1 



CTRL2 



CMPA 


#$18 


Check for CANcel. 


BNE 


CTRL2 


Not CAN? Skip next. 


LDX 


BUFAD 


Was CAN. Get start point. 


STX 


BUFLOC 


Reset "current" location. 


BRA 


BUFIN 


Go get revised data. 


CMPA 


#$0F 


Check for CTRL/0 (backspace). 


BNE 


CTRL3 


Not CTRU0? Skip the following. 


CPX 


BUFAD 


Was CTRL/0. Check current posi- 
tion in buffer. 


BEQ 


BUFIN 


At start? Can't backspace. Forget 
it. 



148 February 1980 @ BYTE Publications Inc Circle 101 On inquiry card. 



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BYTE February 1980 149 



CTRL3 



DEX 




STX 


BUFLOC 


BRA 


BUFIN 


CMPA 


#$12 


BEQ 


LININ 


BRA 


BUFIN 



OK for backspace. Step back 1. 
New "current position." 
Go get corrected input. 
Check for CTRL/R (restart). 
CTRL/R? Start all over. 
All others, back to BUFIN. 



There is nothing seriously wrong with the routine as 
shown, but it uses up 29 bytes in making three com- 
parisons, and all of the operations but one end up by 
branching to BUFIN. Two of the BRA BUFIN instructions 
are unnecessary. Since all of the tests are for equality, the 
quantity in A is obviously going to match at only one 
test. So why bother jumping out early to avoid the other 
tests? 

Another redundancy in this particular instance is not 
quite so obvious unless you see the rest of the routine. 
Note that in the CTRL2 sequence, a backspace is per- 
formed by decrementing the index register and putting 
the index register value into BUFLOC. Evidently, the in- 
dex register carries the "current position" and is equal to 
BUFLOC when first entering the routine. There are two 
STX BUFLOC instructions in the routine. Could they be 
consolidated? The answer is yes, if we do not mind stuff- 
ing the index register into BUFLOC for all incoming 
codes. Try this: 



CTRL1 



CTRL2 



CMPA 


#$18 


BNE 


CTRL2 


LDX 


BUFAD 


CMPA 


#$0F 



Check for CAN. 

Not CAN? Skip. 

Was CAN. Change XR content. 

Check for CTRL/0 (backspace). 



BNE 


CTRL3 


Not CTRL/0. Park XR and check 
for CTRUR. 


CPX 


BUFAD 


Check position. 


BEQ 


CTRL3 


At start? No backspace. Drop on 
through. 


DEX 




Step back 1. 


STX 


BUFLOC 


New or old XR value. 


CMPA 


#$12 


Final test, for CTRL/R. 


BEQ 


LININ 


If CAN or CTRL/0, will fall through 


BRA 


BUFIN 


All except CTRL/R, back to 
BUFIN. 



CTRL3 



Now the routine is down to 23 bytes: possibly a signifi- 
cant saving in a program being squeezed for memory 
space. 

Note that what we are doing here is to trade redundant 
code for redundant operations, a frequently encountered 
tradeoff. To save a few bytes of code we have stretched 
execution time significantly. For keyboard interactive 
routines (as in the example), the execution time is unim- 
portant. In a much used mathematics subroutine on the 
other hand (eg: multiple precision add or multiply), ex- 
ecution time will be much more important, since the 
subroutine may be called thousands of times in one 
calculation, and an optimum tradeoff would be more 
likely in the direction of code redundancy to gain speed 
of execution (counting machine cycles, not bytes of 
memory). 

The next time you are squeezed for space, and speed is 
not critical, take a look at your skip chains: they may be 
able to furnish all the bytes you need, with a little refin- 
ing. ■ 



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150 February 1980 © BYTE Publications lnc 



Circle 102 on inquiry card. 



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(Valid for new Members only. Foreign and Canada add 15'! .) BY-280 

BYTE February 1980 151 










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general purpose utility routines. I/O and interrupt 
programming. How to control and manipulate stacks. 
Code and numeric conversion routines. Plus more! 
For 6502, No. 99, $10.95; for 6800, No. 50, $10.95 
for 8080, No. 60, $10.95; for Z80, No. 75, $14.95 





Z80 Instruction Handbook 

Convenient pocket size guide to the 
powerful Z80 instruction set. Machine 
codes presented in octal and hex format. 
Instructions also indexed alphabetically. 
Only $4.95 No. 20 



Z80 

INSTRUCTION 
HANDBOOK 



Free catalog 

10 pages of 
books for 
business or 
pleasure. 
No. AA 




See SCELBI books at your favorite computer or 
electronics store, or use coupon for direct mail. 

J"" SCELBI Publications 

Si) 20 Hurlbut Street, Elmwood, CT 061 1 

IMPORTANT ORDERING INFO! Include $1.00 ship- 
ping/handling charges for each item. Prices shown are for 
North American customers. Master Charge, VISA, Postal 
and Bank Money Orders preferred. Allow 4 weeks for 
delivery. 

□ No. 10 DNo. 20 DNo. 30 □ No. 40 

□ No. 50 DNo. 60 DNo. 65 DNo. 70 

□ No. 75 DNo. 90 DNo. 99 □ No. AA 

Name (please print) 

Card No. 

Bank No. 

Address 

City /State 

Signature 



. Exp. Date 



Zip 



. Date . 



Circle 104 on inquiry card. 



BYTE February 1980 153 



Event Oueue 



FEBRUARY 1980 



February 6 
Invitational Computer Con- 
ference, Ft Lauderdale FL. 
This conference is directed 
to the quantity buyer and 
will feature the newest 
developments in computer 
and peripheral technology. 
Contact B ] Johnson and 
Associates, 2503 Eastbluff 
Dr, Suite 203, Newport 
Beach CA 92660. 

February 12-14 

Data Communications Con- 
ference and Exhibition, Har- 
bour Castle Hilton, Toronto 
Ontario, Canada. 

Panel sessions, presenta- 
tions, workshops, and 
technical sessions related to 
the field of data communica- 
tions will be featured. Net- 
work control, management, 



performance and architec- 
ture; communications hard- 
ware and software; fiber op- 
tics; distributed data pro- 
cessing; and international 
communications policies are 
some of the subject areas 
that will be discussed. 

The exhibition at the con- 
vention center will feature 
over 100 exhibitors. 

For more information, 
contact Whitsed Publishing 
Ltd, Suite 2504, 2 Bloor St 
W, Toronto, Ontario 
M4W 3E2 CANADA. 



February 11-13 
Programming the 6502 in 
Machine and Assembly 
Language, George 

Washington University, 
Washington DC. This course 
is aimed at engineers, scien- 
tists, mathematicians and 
students who need to learn 



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Shipping & Insurance Extra. 

We carry all major lines such as 

S.D. Systems. Cromemco. IMSAI, Vector Graphics, North Star. Sanyo. ECT. 

TEI. Godbout. Thinker Toys. Hazeltine. IMC 

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bus S-IDD,inc. 

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Interface 201-382-1318 



how to develop special- 
purpose microcomputer 
systems for their own use. 
Familiarity with FORTRAN 
or BASIC will be helpful. 
For more information, con- 
tact Director of Continuing 
Engineering Education, 
George Washinton Universi- 
ty, Washington DC 20052, 
(202) 676-6106. 

February 11-13 

Configuration Management, 

George Washington Univer- 
sity Washington DC. The 
objectives of this course are 
to review the impact of 
latest Department of 
Defense directives and in- 
structions in the configura- 
tion management (CM) area; 
explain policy for practical 
applications; and clarify the 
role of CM in meeting pro- 
gram/project objectives. 
Engineers, program 
managers, production, quali- 
ty control, and purchasing 
people are invited to attend. 
Familiarity with the contents 
of MIL-STD-480 is a pre- 
requisite. Contact the Direc- 
tor, Continuing Engineering 
Education, George 
Washington University, 
Washington DC 20052, (202) 
676-6106. 

February 13-15 

The IEEE International Solid 
State Circuits Conference, 

San Francisco CA. This con- 
ference is a forum for the 
presentation of ad- 
vancements in every aspect 
of solid state circuits. It will 
cover design, performance, 
fabrication, testing, and ap- 
plications in digital, analog, 
microwave, and other areas 
of new solid state circuits, 



device structures, 
phenomena and systems. 
For more information, con- 
tact Lewis Winner, 301 
Almeria Ave, POB 343788, 
Coral Gables FL 33134. 

February 18-21 

European Information 
Management Exhibition and 
Conference, Wembley Con- 
ference Centre, London 
England. This show will 
exhibit microcomputer 
systems and peripheral items 
with demonstrations and ap- 
plications focused on pro- 
blem solving for the 
management executive. Con- 
tact Expoconsul, 420 Lex- 
ington Ave, New York NY 
10017. 

February 22-23 

Louisiana Computer Exposi- 
tion, University of 
Southwestern Louisiana, 
Lafayette LA. This con- 
ference is entitled 
"Distributed Systems Based 
on Mini and Micro Com- 
puters." It will cover pro- 
gramming languages, 
operating systems, evalua- 
tion of distributed systems, 
design criteria for distributed 
systems, and other related 
topics. There will be exhibi- 
tions of equipment and 
papers will be read and 
discussed. For more infor- 
mation, contact the Com- 
puter Science Dept, Univer- 
sity of Southwestern Loui- 
siana, POB 44330, Lafayette 
LA 70504. 

February 25-27 

Communication Networks 
'80, Shoreham Americana 
Hotel, Washington DC. This 
conference and exposition 



In order to gain optimum coverage of your organization's com- 
puter conferences, seminars, workshops, courses, etc, notice should 
reach our office at least three months in advance of the date of the 
event. Entries should be sent to: Event Queue, BYTE Publications, 
70 Main St, Peterborough NH 03458. Each month we publish the 
current contents of the queue for the month of the cover date and the 
two following calendar months. Thus a given event may appear as 
many as three times in this section if it is sent to us far enough in 
advance. 



154 February 1980 © BYTE Publications Inc 



Circle 105 on inquiry card. 



THE ORIGINAL MAGAZINE FOR 
OWNERS OF THE TRS-80 ™* MICROCOMPUTER 



SOFTWARE 

FOR TRS-80" 

OWNERS 



H 



CQMPUTBQMCS 

MONTHLY NEWSMAGAZINE 

Practical Support For Model I & II 



MONTHLY 

NEWSMAGAZINE 

FOR TRS-80" 

OWNERS 



PRACTICAL APPLICATIONS 
BUSINESS 

GAMBLING • GAMES 
EDUCATION 
PERSONAL FINANCE 
BEGINNERS CORNER 
NEW PRODUCTS 
SOFTWARE EXCHANGE 
MARKET PLACE 
QUESTIONS AND ANSWERS 
PROGRAM PRINTOUTS 
AND MORE 



■ ■ ■ 



PROGRAMS AND ARTICLES PUBLISHED IN OUR FIRST 12 ISSUES 
INCLUDE THE FOLLOWING: 

A COMPLETE INCOME TAX PROGRAM (LONG AND SHORT FORM) 

INVENTORY CONTROL 

STOCK MARKET ANALYSIS 

WORD PROCESSING PROGRAM (FOR DISK OR CASSETTE) 

LOWER CASE MODIFICATION FOR YOUR VIDEO MONITOR OR PRINTER 

PAYROLL (FEDERAL TAX WITHHOLDING PROGRAM) 

EXTEND 16 DIGIT ACCURACY TO TRS-80" FUNCTIONS (SUCH AS 

SQUARE ROOTS AND TRIGONOMETRIC FUNCTIONS) 

NEW DISK DRIVES FOR YOUR TRS-80" 

PRINTER OPTIONS AVAILABLE FOR YOUR TRS-80" 

A HORSE SELECTION SYSTEM"*ARITHMETIC TEACHER 

COMPLETE MAILING LIST PROGRAMS (BOTH FOR DISK OR CASSETTE 

SEQUENTIAL AND RANDOM ACCESS) 

RANDOM SAMPLING***BAR GRAPH 

CHECKBOOK MAINTENANCE PROGRAM 

LEVEL II UPDATES***LEVEL II INDEX 

CREDIT CARD INFORMATION STORAGE FILE 

BEGINNER'S GUIDE TO MACHINE LANGUAGE AND ASSEMBLY 

LANGUAGE 

LINE RENUMBERING 

AND CASSETTE TIPS. PROGRAM HINTS. LATEST PRODUCTS 

COMING SOON (GENERAL LEDGER, ACCOUNTS PAYABLE AND 
RECEIVABLE. FORTRAN 80. FINANCIAL APPLICATIONS PACKAGE, 
PROGRAMS FOR HOMEOWNERS. MERGE TWO PROGRAMS. 
STATISTICAL AND MATHEMATICAL PROGRAMS (BOTH 
ELEMENTARY AND ADVANCED) AND 



NOTICE 

Pursuant to a consent judgement entered in the United States District Court for the District of Massachusetts, H & E 
Computronics, Inc. hereby gives notice that it is not and has never been an authorized Radio Shack dealer or outlet, 
that products or services offered for sale or sold by it are not and were not approved or warranted by Radio Shack or 
Tandy Corporation, and that only products or services purchased directly from Radio Shack or its authorized retail 
outlets carry the warranty of Radio Shack and Tandy Corporation. If you have placed an order, still outstanding, with 
H & E Computronics, Inc., for products or services, in the belief that those products or services were manufactured, 
approved or warranted by Radio Shack or Tandy Corporation, you may cancel that order and obtain a full refund of 
any money paid or deposited, simply by writing to the address below. 



&& 



WORD PROCESSING PROGRAM (Cassette or Disk) 

For writing letters, text, mailing lists, etc., with each new subscriptions or renewal. 

LEVEL II RAM TEST (Cassette or Disk) 

Checks random access memory to ensure that alt memory locations are working property. 
DATA MANAGEMENT SYSTEM (Cassette or Disk) -Complete file management (or your TRS-80" 



SEND FOR OUR 36 PAGE SOFTWARE CATALOG (INCLUDING LISTINGS OF HUNDREDS OF TRS-80" PROGRAMS 
AVAILABLE ON CASSETTE AND DISKETTE). $2.00 OR FREE WITH EACH SUBSCRIPTION OR SAMPLE ISSUE. 



CQnPLITfiQMICS 



Box 149 New City, New York 10956 



ONE YEAR SUBSCRIPTION $24 

START MY SUBSCRIPTION WITH ISSUE _ 
NEW SUBSCRIPTION RENEWAL . 



TWO YEAR SUBSCRIPTION $48 



HOUR 
24 ORDER 

LINE 
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SAMPLE OF LATEST ISSUE $4 



(HI July 1978 • »7-January 1979 • »12 June 1979 • »18 January 1980) 



CREDIT CARD NUMBER 

SIGNATURE 

NAME 

ADDRESS 



.EXP DATE. 



*** ADD S6/YEAR (CANADA, MEXICO) ADD $12. YEAR AIR MAIL" OUTSIDE OF U.S.A.. CANADA & MEXICO «*• 

* TRS-80 T " IS A TRADEMARK OF TANDY CORPORATION 



Circle 106 on inquiry card. 



BYTE February 1980 155 



wiJJ cover business com- 
munications. For program 
information, contact the 
Director of Program 
Development, The Con- 
ference Company, 60 Austin 
St, Newton MA 02160. For 
exhibit information, contact 
the national sales manager, 
Communications Networks 
'80, POB 96, Haddon 
Heights NJ 08035. 

February 25-27 

3rd International Learning 
Technology Congress and 
Exposition, Sheraton 



Washington Hotel, 
Washington DC. Applica- 
tions and technologies for 
the use of microcomputers 
and video disks as well as 
traditional technological 
issues in education and 
training will be discussed. In 
addition to the technical ses- 
sions, exhibits will range 
from video disk and media- 
based systems to computer- 
based instruction systems. 
Contact the Society for Ap- 
plied Learning Technology, 
50 Culpeper St, Warrenton 
VA 22186, (703) 347-0055. 



February 25-27 

Microprocessor Peripherals 
Workshop, Montgomery 
AL. This hands-on 
workshop includes 27 hours 
of instruction, with a take- 
home option and one 
microcomputer station for 
every two participants. Con- 
tact Paul A Willis, POB 29, 
Arlington VA 22210. 

February 25-28 

Compcon '80, Jack Tar 
Hotel, San Francisco CA. 
The conference theme is 
"VLSI: New Architectural 




Someday tM 
won't foe a phone 
without one. 



-and under $199. 



The only way to realize the full potential 
of your small business or personal com- 
puter is to tie it in with other computers. 
And the best way to do that is with a Cat 
acoustic modem. 

A Cat modem lets your computer talk 
face to face with any other compatible 
computer or terminal within reach of 
your phone, over standard telephone 
lines. 

You can work at home using the com- 
puter at your office. Send or receive data 
from anywhere. Or swap programs. 



Fast, accurate, reliable - 

Cat. Someday there 
won't be a computer 
without one. 

Novation 

Tie your computer into the world. 

Call for details 

(800) 423-5410 

In California (213) 996-5060 




Available at Hamilton/ Avnet, Kierulff Electronics, Byte Shops, Computerland, 

and your local computer store. 

Novation, Inc., 18664 Oxnard Street, Tarzana, California 91356 



Horizons." It will be 
devoted to developing 
advanced technologies for 
computers. Contact Comp- 
con Spring '80, POB 639, 
Silver Spring MD 20901. 

February 26-28 

Nepcon West '80, Anaheim 
Convention Center, 
Anaheim CA. The con- 
ference and exhibit will deal 
with the latest advances in 
electronics by covering such 
topics as wave soldering, 
etching, automated 
assembly, die attaching, 
hybrid circuit packaging, 
photo lithography, precious 
metal recovery, laser anneal- 
ing, and much more. For 
further information, contact 
ISCM Inc, 222 W Adams St, 
Chicago IL 60606. 

February 26-29 

Office /Korea/80, Korea 
Exhibition Center, Seoul 
Korea. Exhibits at this 
exposition will include the 
range of products needed in 
offices from computers, 
word processing equipment 
and software to stationery, 
supplies, furniture and ser- 
vices. Information about the 
show may be obtained from 
Expoconsul, a division of 
Clapp and Poliak, 420 Lex- 
ington Ave, New York NY 
10017. 

February - August 

Microprocessor Design 
Courses. The course is aim- 
ed at professional design 
engineers and covers funda- 
mentals of microprocessor 
operations, programming, 
architecture and input /out- 
put integration. It will also 
cover Z80 and 8085 pro- 
cessors, working with the 
STD BUS and the designing 
and documenting of soft- 
ware. Tuition for the course 
is $400. The courses will be 
held in major cities 
throughout the US. Contact 
Elma Barnes, PRO-LOG, 
2411 Garden Rd, Monterey 
CA 93940, or phone (408) 
328-4745. 

MARCH 1980 



March 1 

Exploring Small Computers, 



156 February 1980 © BYTE Publications Inc 



Circle 107 on inquiry card. 



I 



I 



'Security... for your 
S-100 hard disk data' 



The availability of fast, reliable, high capacity hard 
disk storage for the S-100 computer market has 
created a wave of excitement. It has also under- 
scored the somber necessity for a reliable means of 
backup. No serious application is practical without 
a dependable, economical method for backup and 
archiving of critical on-line data. 

Now, CSSN breaks the barriers to hard disk ap- 
plications by offering the complete solution for data 
security ... a cartridge tape drive (13.4 megabyte 
capacity), fully S-100 interfaced, and software to 
make it work. -BACKUP IS NOW A REALITY! 




Put your valuable data on-line with a hard disk . . . 
Save it off-line with our Back-Up Solution 



Circle 108 on inquiry card. 




COMPUTER SERVICE SYSTEMS NETWORK 

120 0OYLS1ON STREET • FOURTH FIOOR- DOSION, MASSACHUSETTS 02116 • (617) 482-2343 • TWX (710) 321-1913 INCORPORATED 



Albion College, Albion MI. 
This fair will feature exhibits 
and seminars on microcom- 
puters and their applications 
in business, education, and 
the home. Contact D W 
Kammer, Dept of Physics, 
Albion College, Albion MI 
49224. 

March 3-5 

Office Automation Con- 
ference, Georgia World 
Congress Center, Atlanta 
GA. A combination con- 
ference and exhibition of 
office computer systems has 



been developed to help 
management understand the 
growing technology of 
business computer systems. 
For more information, con- 
tact H A Bruno and 
Associates Inc, 78 E 56th St, 
New York NY 10022. 

March 4 and 5 

8th Annual Midwest Digital 
Equipment Exhibit and 
Seminar, Thunderbird Motel 
Minneapolis MN. Manufac- 
turers of computer ter- 
minals, data communication 
equipment, peripherals, data 



acquisition systems and 
digital test instruments will 
display their products. 
Seminars will be held both 
days. For further informa- 
tion, contact John Bastys 
Countryman Associates Co, 
1821 University Ave, St 
Paul MN 55104. 

March 6-8 

Microprocessor Peripherals 
Workshop, Chattanooga 
TN. See February 25-27 for 
details. 

March 10-12 

1980 National Office Exhibi- 



64KB RAM MEMORIES 

LSI-11 - $750.00 • SBC 80/10 - $750.00 
S-100 - $750.00 • 6800 - $750.00 • 6800-2 - $995.00 



I llll a a p ■ 

iiiiiiiii 

§■■ ii'iiii 
in ■ ill Si 



CI-6800-2 64K x 9 




SiUiUl 
11 ill ill 



CI-S100 64KX8 



■ mini 

■ ■■■■Mi 
■iiilini 
'liiiiiii 



B 



CI-1103 32KX 16 




CI-6800 64K x 8 




CI-8080 64K x 8 



CI-6800-2 — 16KB to 64KB. Plugs 
directly into Motorola's EXORciser I or 
II. Hidden refresh up to 1.5 Mhz. Cycle 
stealing at 2 Mhz. Addressable in 4K 
increments with respect tc VXA or 
VUA. Optional on Board Parity. 64K x 9 
$995.00. 

CI-S100 — 16KB to 64KB. Transparent 
hidden refresh. No wait states at 4 Mhz. 
Compatible with Alpha Micro and all 
Major 8080, 8085 and Z80 Based S100 
Systems. Expandable to 512 K bytes 
thru Bank Selecting. 64K x 8 $750.00. 

CI-1103 — 16KB to 64KB on a single 
dual height board. On board hidden 
refresh. Plugs directly into LSI 11/2, 
H11 or LSI 11/23. Addressable in 2K 
word increments up to 256 K Bytes. 8K 
x 16 $390.00. 32K x 16 $750.00. 

CI-6800 — 16KB to 64KB on a single 
board. On board hidden refresh. Plugs 
directly into EXORciser I and compati- 
ble with Rockwell's System 65. 
Addressable in 4K increments up to 
64K. 16K x 8 $390.00. 64K x 8 $750.00. 

CI-8080 — 16KB to 64KB on a single 
board. Plugs directly into MDS 800 and 
SBC 80/10. Addressable in 4K 
increments up to 64K. 16 KB $390.00. 
64K $750.00. 



€ 



Test and burned-in. Full year warranty. 

Chrislin Industries, Inc. 

Computer Products Division 

31352 Via Colinas • Westlake Village, CA 91361 • 213-991-2254 



tion and Conference, 

Automotive Building, 
Exhibition PI, Toronto 
Canada. Subject areas of the 
conference will include 
energy conservation, small 
business computers, 
micrographics, word pro- 
cessing, telecommunications, 
copiers, office landscaping, 
and many others. There will 
be approximately 100 
exhibitors presenting their 
products and giving 
demonstrations. 

For more information, 
contact Whitsed Publishing 
Ltd, Suite 2504, 2 Bloor St 
W, Toronto, Ontario 
M4W 3E2 CANADA. 

March 14-16 

West Coast Computer Faire, 

Civic Auditorium and 
Brooks Hall, San Francisco 
CA. An expected 15,000 at- 
tendees, over 340 exhibits, 
and more than 100 con- 
ference speakers will 
highlight this year's pro- 
gram. Exhibitor and speaker 
information may be 
requested from the Com- 
puter Faire, 333 Swett Rd, 
Woodside CA 94062. 

March 17-20 

Interface '80, Miami Beach 
Convention Center, Miami 
Beach FL. This conference 
and exposition is devoted to 
data communications, 
distributed data processing, 
and networking. Approx- 
imately 1000 exhibitors are 
anticipated and attendance is 
expected to exceed 12,000. 
For information, contact 
Interface '80, 160 Speen St, 
Framingham MA 01701. 

March 17-21 

Applied Time Series 
Analysis, University of 
California at Los Angeles 
CA. This course is designed 
for engineers, scientists, pro- 
grammers, economists and 
other users of digital time 
series who require modern 
methods of data analysis 
using the fast Fourier 
transform (FFT), digital 
filtering, power spectral den- 
sities and correlation func- 
tions. The lectures cover 
topics relating to the Fourier 
transform, sampling linear 
systems, convolution, 
covariance, digital filtering, 



158 February 1980 © BYTE Publications Inc 



Circle 109 on inquiry card. 





• ?"*">?!* 






*r* ? «T 




CJ® 



W-^ 




The line your reputation should be on. 



When a computer supplier or retailer sells equipment, 
his reputation is on the line. 

And when the customer has to justify his investment 
decision, his reputation is on the line too. 

So, naturally, everybody's a lot better off on a reliable 
line. Like ours. 

With a name like Industrial Micro Systems, we 
wouldn't think of building anything short of industrial 
standards . . . even our S-100 products. 
No short cuts or jumpers. 

All of our boards — CPU, memory and controllers — 
are made from real fiberglass instead of a plastic 
substitute. And contacts are gold plated over a copper- 
ion barrier of nickel. 

Every disk enclosure features a heavy-gauge steel 
chassis, and a heavy duty power supply. Built to take it. 

Then come our complete systems. Aside from the 
disk drives, we manufacture every component that goes 
into them. Even the desk that goes around them. So 



we can vouch for rugged reliability inside and out. 
Two complete systems: 

Our new Series 5000 features a megabyte of storage 
on integral mini-floppies. And our Series 8000 is all 
business too. It can handle up to three megabytes on 
8-inch drives. A large library of software, growing daily, 
includes CP/Mf PASCAL, and FAMOS?* 
Breaking the 64k barrier. 

Using Industrial Micro Systems 32k memory boards 
with Memory Management, our systems can handle 
up to 576k RAM internally. 
More in store. 

That's not the end of the line. It's growing all the time, 
along with our reputation for quality. Put your reputation 
on the line. Our line. 

For more details just call or write. Supplier/dealer 
inquiries welcomed. 

Industrial Micro Systems, 628 N. Eckhoff, Orange, 
CA 92668.(714) 978-6966 



INDUSTRIAL MICRO SYSTEMS 



The great unknown. 



Trademark of Digital Research "Trademark of MV/T Systems 



Circle 110 on inquiry card. 



BYTE February 1980 159 



power and cross-spectral 
density functions, and 
introductions to new 
methods in spectral analysis 
and rotating machinery 
analysis. For more informa- 
tion, contact UCLA Exten- 
sion, 10995 Le Conte Ave, 
Los Angeles CA 90024. 

March 20 
Electronic Road Shows, 

Castaways Restaurant, Bur- 
bank CA. This traveling ex- 
hibition of components, 
materials, and instruments is 
being produced by the 
Electronic Representatives 
Association (ERA). Over 
eighty ERA member firms 
will participate, and pro- 
ducts from over 700 elec- 
tronic companies will be 
displayed. For more infor- 
mation, contact the 
Southern California ERA 
office 20969 Ventura Blvd, 
Suite 9, Woodland Hills CA 
91364. 

March 24-26 
Data Entry Management and 
Supervision Seminar, Cherry 
Hill NJ. This course deals 
with the practical aspects of 
data entry, and the pro- 
blems encountered that are 
common to supervisors and 
managers. Concepts, tech- 
niques, motivation, training, 
and productivity will be 
covered. The fee is $415 for 
subscribers of MIC publica- 
tions and $445 for non- 
subscribers. For more infor- 
mation, contact MIC, 140 
Barclay Ctr, Cherry Hill NJ 
08034. 

March 24-28 

Fourth European Conference 
on Electrotechnics, Stutt- 
gart. This conference will 
review recent developments, 
trends, and applications in 
the field of microelectronics. 
Microprocessors, computer 
communication, industrial 
electronics applications of 
microelectronics in the 
automobile and in medicine, 
and other topics will be 
covered. The conference 
language will be English. 
Contact Professor Dr W E 
Proebster, IBM Deutschland 



GmbH, Postfach 80 08 80, 
D-7000 Stuttgart 80 
GERMANY (BRD). 

March 26-28 
Viewdata '80, Wembley 
Conference Centre, London 
England. Viewdata 80 is an 
international exhibition and 
conference on video-based 
systems and microcomputer 
industries. The British Post 
Office is presenting the 
Prestel Show which is about 
electronic mail services. 
Contact TMAC, 680 
Beach St, Suite 428, San 
Francisco CA 94109. 

March 30 
Greater Baltimore Hamboree 
and Computerfest, 

Maryland State Fairgrounds, 
Timonium MD. Personal, 
dealer, and small business 
computer displays and ex- 
hibits will be featured. Space 
is available outside for 
tailgate sales and swaps. For 
more information, contact 
Joseph Lochte Jr, 2136 Pine 
Valley Dr, Timonium MD 
21093. 

March - lune 

Computer and Office 
Systems Expo and Con- 
ference. This is an exposi- 
tion for marketers of office 
systems equipment. The 
show and conference will 
focus on the local problems 
and opportunities of each 
region. The exposition and 
conference will be held in 
major cities around the na- 
tion. Contact The Con- 
ference Co, 60 Austin St, 
Newton MA 02160, or 
phone (617) 964-4550. 



APRIL 1980 



April 1 and 2 

Southeast Printed Circuits 
and Microelectronics Exposi- 
tion, Sheraton-Twin Towers 
Convention Center, Orlando 
FL. This show is a specializ- 
ed event devoted entirely to 
the packaging, production 
and testing of printed cir- 
cuits, multilayers, semicon- 
ductor devices, and hybrids 



in the Southeast. Con- 
ferences are aimed at elec- 
tronics specialists. Contact 
ISCM, 222 W Adams St, 
Chicago IL 60606. 

Afjril 9-11 

The Practical APL Con- 
ference, Washington DC. 
This conference is addressed 
to business executives and 
systems designers. For more 
information, contact Joan 
Gurgold, STSC, 7 Holland 
Ave, White Plains NY 
10603. 

April 9-11 
International Conference on 
Acoustics, Speech and 
Signal Processing, Fairmont 
Hotel, Denver CO. 

The IEEE Acoustics, 
Speech and Signal Process- 
ing Society is sponsoring 
this conference devoted to 
experimental and theoretical 
aspects of signal processing, 
speech, and acoustics. For 
more information, contact 
IEEE, 1100 14th St, Denver 
CO 80202. 

April 11-12 

10th Annual Virginia Com- 
puter Users Conference. This 
conference is sponsored by 
the Virginia Tech ACM stu- 
dent chapter. The topics of 
discussion will be program- 
ming languages and system 
and personnel management. 
For more information, con- 
tact VCUC10, 562 McBryde 
Hall, VPI&SU, Blacksburg 
V A 24061. 

April 13-16 

A Gateway to the Use of 
Computers in Education, 
Chase Park Plaza Hotel, St 
Louis MO. The purpose of 
this convention is to provide 
a forum for the exchange of 
information and ideas be- 
tween individuals, to inform 
educators of developments 
in computer technology, and 
to expose participants to in- 
novations in computing 
which can be utilized in the 
field of education. 

Educators are encouraged 
to exhibit and make presen- 
tations of instructional 
microprocessor materials 



during the convention. Con- 
tact the Association for 
Educational Data Systems 
(AEDS), POB 951, Rolla 
MO 65401. 

April 14-18 

High-Speed Computer 
Organization, 6266 Boelter 
Hall, UCLA Extension, Los 
Angeles CA. This course is 
for computer designers, 
system architects, project 
leaders and managers. The 
course provides an 
understanding of the prin- 
ciples of high-speed com- 
puter organization and their 
use in cost-effective systems. 
Several commercial and 
paper high-speed computers 
are presented and compared. 

For more information, 
contact UCLA Extension at 
POB 24901, Dept K, UCLA 
Extension, Los Angeles CA 
90024. 

April 21-25 
National Micrographics 
Association 29th Annual 
Conference and Exposition, 

Sheraton Center Hotel and 
Coliseum, New York NY. 
The theme for the show is 
"Focus on Productivity in 
Office Management." 
Highlighting the conference 
and exposition will be 
presentations and talks con- 
cerning the use in offices for 
computer systems and 
related items. 

For more information, 
contact the Conference 
Dept, National 
Micrographics Association, 
8719 Colesville Rd, Silver 
Spring MD 20910. 

April 23-25 
International DP Training 
Conference, Hyatt Regency, 
Chicago IL. The theme for 
this event will be "The 
1980s: The Information 
Decade." The conference is 
a symposium for data pro- 
cessing experts and cor- 
porate training executives. 
For information, contact 
Deltak Inc, 1220 Kensington 
Rd, Oak Brook IL 60521. ■ 



160 February 1980 © BYTE Publications Inc 



MICROSOFT CONSUMER PRODUCTS 

CONTINUING THE 
MICROSOFT TRADITION 



Microsoft set the standard in microcomputer system software. We know more 
about the structure and capabilities of today's microcomputers than anyone else. 
And now we're using that power in a whole new way! 



Announcing Microsoft Consumer Products. Dis- 
tinctive software packages backed by the Microsoft 
name. Each is created by a top-notch programmer 
and comes to you fully documented, at a cost you 
can afford. 

Microsoft Editor/Assembler-Plus." Now get every 
feature of Radio Shack's Editor/ Assembler andT-Bug 
all in one package. PLUS— many "big computer" 
features to simplify your programming, editing and 
debugging. All in a low cost cassette package. 
Don't waste time creating both source and object 
tapes— Assembler-Plus assembles directly into mem- 
ory. Supports macros and conditional assembly, too. 
Editor-Plus simplifies editing with extra commands 
like Substitute, Move, Copy and Extend. And 
Z-Bug,'" the most powerful debugger ever available 
for the TRS-80, has single step execution, direct 
execution in calculator mode and symbolic refer- 
ences. And, you can use up to 8 breakpoints at a 
time, with no need to remove a breakpoint before 
proceeding. For the 16K, Level II, cassette TRS-80. 
Priced at $29.95. 

Microsoft Adventure. Only Microsoft offers Adven- 
ture complete, as originally written for the DEC 
PDP-10, now implemented on personal computers. 
The ultimate fantasy/logic game. Adventure allows 
you to explore the depths of the "Colossal Cave',' 
collecting treasures and magic, solving puzzles, 
avoiding hazards and adversaries— including the 
dreaded killer dwarves. Don't be fooled by imita- 
tion or incomplete versions. Only Microsoft has it all. 
Adventure fills an entire disk with everything you 
need for your exploration. Written by Gordon Letwin, 
of SOFTWIN, Associates. Adventure for the TRS-80 re- 
quires a single-disk, 32K system. For the Apple II,** a 
single-disk, 32K system with either the standard disk 
or language card system. For just $29.95. 



Microsoft Typing Tutor. There's no easier way to mas- 
ter your keyboard! Faster and more efficient than 
any other teaching method, Typing Tutor helps you if 
you're starting from scratch or simply building 
speed. The secret lies in Typing Tutor's exclusive TRM '" 
or "Time Response Monitoring" software. TRM moni- 
tors your keyboard 20 times per second so the com- 
puter can evaluate your skill. Your speed. Your errors. 
Your weakest keys. Typing Tutor tells you where you 
stand then automatically adjusts itself to help you 
improve. Written by Dick Ainsworth and Al Baker of 
the Image Producers, Inc. For the Apple II with 16K 
and Apple BASIC or the TRS-80 with 16K and Level II 
BASIC. Priced at $14.95. 

Microsoft Level III BASIC. Upgrade your Level II 
TRS-80 and increase your programming efficiency 
without additional hardware. Microsoft Level III 
loads from cassette tape on top of the Level II ROM. 
It gives you every feature of Disk BASIC except disk 
file commands. But that's not all— Level Ill's high- 
speed graphics turn your TRS-80* into a virtual elec- 
tronic drawing board. And there's program renum- 
bering, long error messages, quick shift-key entries, 
time-limit INPUT statements and many more fea- 
tures. System requirements: Level II BASIC and 16K. 
Occupies 5.2K RAM. Priced at $49.95. 

Where To Buy. Microsoft Consumer Products are 
sold by computer retailers nationwide. If your local 
computer store doesn't have them, call us. Phone 
[206] 454-1315. Or write Microsoft Consumer Products, 
10800 Northeast Eighth, Suite 819, Bellevue, WA 98004. 



TRS-80 is a trademark of Radio Shack Corp. "Appie II is a trade- 
mark of Apple Computer, Inc.,'" Editor/Assembler-Plus and Z-Bug 
are trademarks of Microsoft. TRM js^ a trademark of The Image 
Producers, Inc. 




Circle 111 on inquiry card. 



BYTE February 1980 161 



BYTE's Bits 



Ken Bowles' 

Current Activities: 

Training in Pascal... 

notes by C Helmers 

In the last year or so, we 
have been placing much em- 
phasis on the computer 
language Pascal, with parti- 
cular attention to the 
University of California at 
San Diego (UCSD) system 
which, by being available, 
has become a de facto stan- 
dard for small-computer, 
Pascal-oriented systems soft- 
ware. Dr Kenneth Bowles of 
UCSD was the originator of 
the project which generated 
the UCSD system, and he is 
its prime mover. 

As a professor of Com- 
puter Science and Electrical 
Engineering at UCSD, Dr 
Bowles has been instru- 
mental in the implementa- 
tion of Pascal on small com- 
puters, starting with the LSI- 
11-based Terak machine, 
and now including all the 
major 8-bit microprocessor 
designs. Since its inception 
in 1974, UCSD Pascal has 
been licensed to more than 
1000 individuals and 
organizations. With the re- 
cent availability on the Ap- 
ple II, North Star Horizon, 
and other major personal 
computer systems, the 
UCSD software has become 
a major, machine- 
independent, industry-wide 
standard for an operating 
system and compiler. Due to 
the nonprofit status of the 
University of California, the 
system has been recently 
spun off to an independent 
software company, Softech 
Micro Systems of San 
Diego, California. 

Dr Bowles' purposes in 
developing the UCSD Pascal 
system included the desire to 
make widely available a 
convenient and machine- 
independent structured pro- 
gramming language and 
operating system. The non- 




Photo 1: The hands-on aspect of Ken's Integrated Computer 
Systems continuing education course on Pascal is provided by 
use of a number of portable computers such as the Apple II 
Pascal system. Ken is shown here demonstrating a point to some 
students. 



commercial intellectual suc- 
cess of the Bell Laboratories 
UNIX operating system, 
with its language C, was 
doubtlessly an inspiration 
for the UCSD concept of a 
machine-independent 
operating system and 
language. As a teaching 
device in schools and 
universities, the intellectual 
popularity of the Pascal 
language was part of the 
reason for choosing it as a 
suitable vehicle for 
widespread teaching of pro- 
gramming concepts and con- 
venient application program- 
ming. Also key to the choice 
of Pascal as a language to 



pursue was the fact that its 
originators, Niklaus Wirth 
and Kathleen Jensen, had 
designed a concise but 
robust high-level language 
which was first (and most 
typically) implemented 
through the highly machine- 
independent technique of 
simulating a virtual 
"P-machine" on conven- 
tional machines. The rest is 
history. An operating 
system with many interac- 
tive features, editors and file 
management programs was 
written in Pascal along with 
the compiler; the code was 
made available and when 
the response got too large 



for the university's "non- 
profit" political environ- 
ment, the system's 
marketing and maintenance 
operations were assigned to 
a commercial company. 

Ken is now participating 
in the continuing education 
programs of a company 
called Integrated Computer 
Systems Inc. This company 
specializes in intensive train- 
ing courses given in major 
cities, as a sort of travel- 
ing road show intended for 
potential users of high- 
technology tools such as the 
Pascal language. Ken's 
course is designed for 
engineers, scientists and pro- 
grammer/analysts who plan 
to use Pascal for the 
development of software 
systems. The class features 
exercises involving text pro- 
cessing, interactive data 
collection, dynamic graphic 
display and real-time control 
applications. Class sizes are 
strictly limited to (typically) 
36 students in order to pro- 
vide maximum hands-on 
activity. 

The course is operated for 
four days (Tuesday thru 
Friday). Each attendee 
receives a diploma and one 
Continuing Education Unit 
for each 10 hours of 
participation. The Continu- 
ing Education Unit is a na- 
tionally recognized credit 
awarded by universities and 
educational organizations 
for participation in such 
programs. (Scheduled time 
each day of the four-day 
schedule is from 9 AM to 6 
PM, so in principle one 
could obtain 3.6 such units 
from the course given atten- 
dance of the full four-day 
schedule.) The price is $795 
including all materials, lun- 
cheons and coffee breaks. 
The following dates are 
presently scheduled: 

San Francisco CA: 
February 12-15, 1980 



162 February 1980 © BYTE Publications Inc 



PUTTING IT ALL TOGETHER 




Four-User North Star Horizon with 
29 Megabyte Hard Disk Interface 



inCLUDIHO: 

48K RAM per user 

Two 360K 5'A" disk drives (as many 
as four, optional) 

Two printers: 
One Texas Instruments TI 810 dot 
matrix, 150 character per second, 
bi-directional, tractor feed printer 
with all available options 
One NEC Spinwriter 5510 docu- 
ment quality, full-character print- 
er with friction feed and tractor 
feed 

Deluxe printer stands and paper 
trays for both printers 

One Discus 29 megabyte (26 mega- 
byte formatted) Winchester technol- 
ogy, fixed hard disk unit with con- 
troller, cabinet, power supply, all 
cables, ports and connectors, com- 
pletely interfaced to DOS and BASIC, 
CP/M, PASCAL and Micro Mike's in- 
terrupt-driven, bank-switching time- 
sharing (as many as four 29 mega- 
byte hard disk units, seven users, 
optional) 

One custom computer/hard disk 
desk, Executive model, three CRT 
stands, thirty 5'A'' diskettes 




"Micro Mike's, Incorporated Pro- 
gram Library Membership, includ- 
ing: 

General Ledger 

Accounts Receivable 

Accounts Payable 

Inventory 

CSUB (Common SUBroutines) 

Payroll 

Mail list 

Word Processing/Text Editing 

Project Cattle Profits 

Timesharing 

DOSCHQ (eight inch drive inter- 
face to DOS and BASIC) 

Commodities Charts 

and many outstanding utilities 
programs and public domain 
software 
•All programs available separately. 
Total System $23,719 

Micro Mike's, Inc. thoroughly "burns 
in" and tests all systems delivered 
as integrated hardware/ software 
systems, under timesharing condi- 
tions, the ultimate test of a com- 
plete computer system. This "burn- 
ing-in" and testing procedure con- 
tinues, non-stop, for a minimum of 
three days and nights, insuring the 
end user the highest quality, trou- 
ble-free integrated hardware/ soft- 
ware system possible. 

Micro Mike's, Inc. will, for a fee, de- 
liver and set up a system anywhere 
in the USA. Personal user training 
and/or custom programming is also 
available. 



Complete north Star 

Horizon Service Center 

Call or write for 

descriptive literature 



*****••* 

Discus 29 megabyte Winchester 
technology fixed, sealed hard disk 
units completely interfaced to DOS 
and BASIC, CP/M and PASCAL for 
most S-100 buss computer systems, 
ready to go, including controller, 
cabinet and power supply, all 
cables, ports and connectors $5,495 

Additional 29 megabyte drive, cabi- 
net and power supply $4,495 

******** 

Micro Mike's, Inc. offers a complete 
selection of top-notch business soft- 
ware. Among comprehensive pro- 
grams are: 

• Time and Expense package for ac- 
countants, attorneys, and other pro- 
fessionals • Patient Daily Record 
Program (Doctor/ Patient Ledger) for 
Physicians • Land Subdivision pack- 
age • Pharmacy • Motel Reservation 
with Night Audit • Banker's Trust • 
Feedlot • Oil/Qas Producer's pack- 
age • many more 

******** 

IN STOCK: 

North Star Horizons 

Discus double density or quad capa- 
city eight inch drives for S-100 
buss systems 

Printers: Texas Instruments TI 810, 
NEC Spinwriter, IDS-440 Paper 
Tiger 

Armadillo Armor 5'/4" protective 

diskette shipping cartons .... $45 

per hundred 

Used Intertec Intertube CRTs, as-is 
condition, close-out $495 



JlUkh 



68 



MICRO MIKE'S, INCORPORATED 

905 South Buchanan 
Amarillo, Texas 79101 U.S.A. 
806-372-3633 



making technology uncomplicated . . . for People 



Circle 112 on inquiry card. 



BYTE February 1980 163 



Circle 113 on inquiry card. 



FOR YOU 
YOUR WIFE 
YOUR CHILD 
YOUR HOME 
YOUR SCHOOL 
YOUR BUSINESS 

[A Computer System Both 
Practical and Affordable! 

: Many uses for your computer, ■ Word 
^Processing ■ Accounting ■ Bookkeeping! 
i Games ■ Personal Records ■ Menul 
iPlanning ■ EducationalDevelopment 
■ Tax Preparation ■ Homework, etc. 

BYTE SHOP EAST offers a wide selection of hardware to meet 
your specific needs; SORCERER, PET, APPLE, NORTH STAR, 
IMSAI, DIGITAL, and many, many others. BYTE SHOP EASThas | 

a complete library of books and magazines to meet your needs. 

Come in to our computer stores for a FREE demonstration! 

BVTE SHOP EflSTJ 



130 East 40th St. 
(Corner of Lexington Ave.) 
New York 10016" 
Tues.-Fri. 10- 6 Sat. 10- 5 
(212) 889-4204 



2721 Hempstead Turnpike 
(Just East of Wantagh Pkwy) 
Levittown, N.Y. 11756 
Tues.-Fri. 12 - 8 Sat. 10 - 5 
(516) 731-8116 



New 
Robotype 

Turns your 
typewriter 



into a 
quality 
i output 
printer! 



• easily connects to any computer 

• serial and parallel interface 

• all electronics included — ready to use from package 

• connects to IBM Selectric TJ typewriter in just one minute 

• adapts to a variety of typewriters— no modifications 

• compatible with Radio Shack TRS-80, Apple II, Pet, etc. 

• Centronics interface compatible 

• available from stock in 30 days 

Put a Robotype to work on your typewriter for under 

$1,000. Call (614) 436-3163 today! 

Dealer, distributors, and word processor OEM inquiries welcome. 



£v Robotype 




TM 



(A trademark of 
Compu-Matics, Inc.) 



Applied 
Computer 
Systems, Inc. 



77 East Wilson Bridge Road • Worthington, Ohio 43085 



Washington DC: 
March 4-7, 1980 

Los Angeles CA: 
March 11-14, 1980 

Atlanta GA: 

March 18-21, 1980 

Houston TX: 

April 15-18, 1980 

Boston MA: 

April 29-May 2, 1980 

San Diego CA: 
May 6-9, 1980 

For further information 
and enrollment forms, con- 
tact Integrated Computer 
Systems Inc, 3304 Pico Blvd, 
Santa Monica CA 90405, or 
phone (213) 450-2060. 



Call for Papers — 
1980 LISP Conference 

A call for papers has been 
announced for the August 
24 thru August 27 LISP 
Conference at Stanford 
University. The topics 
should cover languages and 
theory, programming 
aspects, architecture, and 
applications of LISP. Other 
related items are welcome. 
Authors are requested to 
send four copies of a full 
draft paper not exceeding 
4500 words, and a one-page 
abstract, by March 14, 1980 
to the Conference Head. 
The abstract should provide 
sufficient detail to allow the 
committee to apply uniform 
criteria for acceptance. 
Authors will be notified of 
acceptance or rejection by 
May 16, 1980. For inclusion 
in the proceedings, final 
papers are due by June 27, 
1980. Send papers to John R 
Allen, Stanford Artificial In- 
telligence Lab, Stanford 
University, Stanford CA 
94305, or phone (415) 
497-4971 for further details. 



Bulletin Board Notes 

A computerized bulletin 
board system (CBBS) is now 
in operation in Cambridge 
Massachusetts, thanks to the 
diligent labors of David Mit- 
ton and other members of 



the New England Computer 
Society. Running the CBBS 
code written by Ward 
Christensen and Randy 
Suess on a Processor 
Technology Sol-20, the 
system is available around 
the clock. Two data rates 
are supported, 110 and 300 
bits per second (bps). The 
telephone number to access 
the system is (617) 864-3819. 

A description of a CBBS 
appeared in the article 
"Hobbyist Computerized 
Bulletin Board," by 
Christensen and Suess, in 
the November 1978 BYTE, 
page 150. 



Call a Computer 
for Computers 

If you want to purchase 
computer equipment, soft- 
ware, terminals, supplies, or 
any other related equip- 
ment, call (813) 885-4811 
and talk to a computer. 
There is no charge but calls 
are limited to 3 minutes; 
however, if necessary, you 
can call again. There should 
be a listing of the items 
needed. To access the 
system: set your terminal for 
300 bps operation, set the 
modem for full duplex 
originate operation, call 
(813) 885-4811, after the ter- 
minal is on-line enter any 
character and a carriage 
return. The system will res- 
pond "PLEASE LOG IN", 
then enter the string 
" HELLO-Z999, " (only the 
characters underlined), then 
follow the directions on the 
terminal to search the file. 

To place a listing with the 
service, contact Basic Online 
Software Systems Corp, 
POB 22412, Tampa FL 
33622. 



Cafeteria Chain Pioneers 
Computerized Cost 
Control of Recipes 

A chain of cafeterias serv- 
ing the Los Angeles public 
has developed a restaurant 
menu-planning system to 
minimize the effects of rapid 
inflation and skittish 
agricultural commodity 
prices. 



164 February 1980 © BYTE Publications Inc 



Circle 114 on inquiry card. 











Model DMB-6400 Series dynamic 64k byte RAMS incorporate the 
features which are standard in the DM-6400 Series and adds 
bank select for multi-user-timesharins applications. 

• Four (4) 16k byte, functionally 
independent memory banks. 

• Eight (8) 64k byte banks of mem- 



• ALPHA MICRO, CROMEMCO, 
and NORTH STAR output port 
bank select. 

• Memory bank size can be incre- 
mented to 64k bytes in 16k 
increments. 



ory per output port for ex pan 
sion to 512k bytes for each 
output port. 



Model DM-6400 Series dynamic 64k memory boards feature IEEE 
S-100 compatible timing and on board transparent refresh. 

• Memory selectable and deselec- • 25 MHz on board crystal oscillator 

table in 4k byte increments. for independent timing. 

DMB-6400 and DM-6400 Common Features: 



• 4 MHz Z80 operation with no wait 
states. 

• Tested and bumed-in. 

ONE YEAR GUARANTEE 



• Low power- 8 watts maximum. 

• Reliable, expandable memories. 



THE FOLLOWING PRODUCTS ARE AVAILABLE 
□ DMB-3200/32KRAM 



□ DMB-6400/64KRAM □ DMB-3200/32K RAM □ DM-6400/64K RAM 

□ DMB-4800/48KRAM □ DM-4800/48K RAM 

ATTRACTIVELY DISCOUNTED OEM AND DEALER QUANTITY PRICES AVAILABLE 



D DM-3200/32KRAM 



U.K. & EUROPEAN REPRESENTATIVE: 

ABACUS COMPUTERS LTD. 
62, NEW CAVENDISH STREET 
LONDON. W1M 7LD U.K. 
TEL: 01-580/8841 TELEX: 881-3085 

AUSTRALIAN REPRESENTATIVE: 

COMPUTERLAND OF MELBOURNE 
555 COLLINS STREET 
MELBOURNE, VIC3000 
TEL: 625581 



MEASUREMENT 

systems &. controls 

incorporated 

867 North Main Street • Orange, CA 92668 
Telephone: 714/633-4460 



Circle 115 on inquiry card. 



BYTE February 1980 165 



The menu planners at 
Clifton's Cafeterias enter 
current commodity pricing 
information into a Data 
General Corp computer 
system, and obtain the exact 
cost for each of 2500 recipes 
possible on Clifton's menus. 

The CS/40 system has 
reduced the menu recost 
time from 9 months to 6 
hours and could save the 
cafeteria chain about 
$50,000 annually. In addi- 
tion to the food purchasing 
and recipe maintenance, the 
system can handle the 



payroll for 600 employees 
and do accounts payable, a 
general ledger and a cash 
journal. The system includes 
a printer, four video ter- 
minals, a magnetic tape 
drive and a potential 250 K 
bytes of memory storage on 
the disk drives. 

The CS/40 business 
system has reduced errors, 
provided current informa- 
tion, and has allowed for 
more interesting and more 
varied menus. 

Contact the P R Dept, 
Data General Corp, Rt 9, 



Westboro MA 01581, for 
more information. 



Chicago Library Offers 

Public Computers and a 

Computerized Reference 

Service 

To permit the public to 
experience computer-assisted 
instruction (CAI), to per- 
form basic computer 
routines and to gain ex- 
perience in programming, 
microcomputers have been 
installed in the Business/- 



YOU THINK YOU'VE SEEN WORD 
PROCESSING SOFTWARE? 



The 



magic wand; 



Word Processing 



System offers you the best features of any system 
in the micro market 



FEATURES INCLUDE: 
Full-screen text editor 

Simple, control key operation 
Edit programs as well as text 

Assemble, compile or run programs 

without modification 
Files larger than memory 

Files up to 256K 
Library files 

Merge part or all of one file with 

another 
Spool printing 

Print a file while editing another 
Easy page formatting 

Simple commands set margins, page 

length, etc. 
Override commands at run-time 

Give any command from the key- 
board as well as in file 
Variable pitch control 

Change pitch in mid-line, even 

mid-word 
Up to 1 28 user-defined variables 

String, numeric or dollar format 
Form letter generation from external 
data files 

Compatible with both sequential and 

fixed-record files 
Conditional commands 

Any command may be conditional 
Print to disk and/or printer 

Save all or part of output on disk 
Switch from specialty printer to CP/M 
list device 

Print the same file on either specialty 

or standard printer 



EASE OF OPERATION 

With all its power, the MAGIC WAND is 
remarkably easy to use. This is no acci- 
dent. The command structure is designed 
to be flexible and logical so that you can 
perform basic functions with a minimum of 
commands. 

We have included in the manual a step- 
by-step instructional program, for the per- 
son who has never used a word-proces- 
sor before. The trainee uses sample files 
from the system disk and compares his 
work to simulated screens and printouts. 

In addition to the lessons, the manual 
has a complete documentation of the 
command structure, special notes for pro- 
grammers, an introduction to CP/M for 
non-programmers and a glossary. The 
manual is typeset, rather than typewritten, 
for greater legibility. 

We have written the manual in non- 
technical English, because we want you 
to read it. We don't overload you with a 
bunch of jargon that could confuse even a 
PhD in Computer Sciences. 

We send out newsletters so that users 
of the MAGIC WAND can learn special 
applications of the print commands. For 
example, we might show you how to cre- 
ate a mailing list or set up an index for 
a file. 

In short, we've done everything we can 
to make things easy for you. Because the 
best software in the world is just a bunch 
of code if you can't use it. 



For more information , call or write: 

srcuxW business ap^icaXious, u*.c. 

3220 Louisiana • Suite 205 • Houston, Texas 77006 • 713-528-5158 



Science/Technology Divi- 
sion of the Central Library, 
the Popular Library in the 
Cultural Center, the Wood- 
son Regional Library, and 
the Lincoln Park Branch, all 
agencies of the Chicago 
Public Library. 

The system includes video 
displays, software, training 
manuals, but no printers. It 
runs on BASIC, and has 
8 K bytes of programmable 
memory. Engineers, 
businessmen, students 
developing chess skills, and 
people balancing their 
checkbooks have been using 
the devices. If usage in- 
creases substantially, the 
Library will consider the 
purchase of additional units 
for other branches in the 
library system. 

Their other service pro- 
vides millions of references 
to books, periodicals, 
reports, all on a wide range 
of subjects. Where manual 
research can take hours or 
even days, the computerized 
service can reduce to only a 
few minutes the time usually 
required for a thorough 
research study. For this ser- 
vice, the first 5 minutes of 
computer time are free and 
each additional minute costs 
$1.50. Contact the 
Business/Science/Tech- 
nology Division in the Cen- 
tral Library at 425 N 
Michigan Ave, Chicago IL 
60611, or call (312) 
269-2915. 

Apple Education 

Foundation Advances 

Learning Methods 

Through Microcomputers 

Initially funded by Apple 
Computer, the nonprofit 
foundation will offer sup- 
port and resources to 
organizations and in- 
dividuals who are pioneering 
learning methods through 
the use of microcomputers. 
Funding authorizations 
through 1980 are valued in 
excess of $250,000. The 
foundation will distribute 
hardware equipment for 
both developmental and 
demonstration projects in- 
volved in producing instruc- 
tional computing materials. 
The foundation's primary 



166 February 1980 © BYTE Publications Inc 



Circle 116 on inquiry card. 




after 





BATTERY SUPPORTED 
CALENDAR CLOCKS 



PDP-11* 

TCU-100*$495 

■ Provides month, day, hour, minute and second. 

■ Can interrupt on date/time, or periodic intervals. 

TCU-150-$460 

■ Provides year, month, day, hour, minute and 
second. 

■ Automatic leap year. 

■ Patches for RSX-11M, RT-11 FB/SJ V02, V03 
and UNIX. 

LSI-11/2* 

TCU-50D • $325 

■ Provides month, day, hour, minute and second. 

■ Dual size board. 

■ Patches for RT-11 SJ/FB V02, V03B. 

Lockheed SUE 

TCU-200 • $550 

■ Provides year, month, day, hour, minute, second 
and milli-second. 

■ Interval interrupts between 1/1024 seconds and 
64 seconds. 

Computer Automation (Naked Mini) 

TCU-310-$385 

■ Provides year, month, day, hour, minute and 
second. 

'Trademark of Digital Equipment Corporation 




Multi-Bus** 

TCU-410*$325 

■ Provides year, month, day, hour, minute and 
second. 

■ SBC/BLC compatible. 

HP 2100 

TCU-2100*$395 

■ Correct time restored after power failure. 

■ Compatible with the HP TBG card. 

Serial Clock (RS 232 or 20 mA) 

SLC-1 • $640 

■ Connects between any terminal and host computer. 

■ Provides date, time and more! 

All Digital Pathways TCUs have on board NICAD 
batteries to maintain time and date during power 
down. Timing is provided by a crystal controlled 
oscillator. Prices are U.S. domestic single piece. 
Quantity discounts available. 

For more information on these products, contact: 
Digital Pathways Inc. 
4151 Middlefield Road 
Palo Alto, CA 94306 
Phone: (415) 493-5544 



* 'Trademark of Intel Corporation 
** "Trademark of Computer Automation Incorporated 



DIGITAL PATHWAYS 



Circle 117 on inquiry card. 



BYTE February 1980 167 



Circle 118 on inquiry card. 



Kill Surges 
Like Lightning! 







Surge Sentry 120 works in parallel with the power 
line to shunt destructive power surges in less than 
1 nanosecond! Triggers at 10% above the nominal 
peak voltage. Plugs into any standard 120-volt 
outlet for immediate protection. 

Ideal for small computers, communications, 
medical, and other sensitive electronic equipment. 
Suggested retail price $89.50. OEM model also 
available. Call or write: 

l] [< Z R&K Enterprises 

643 South 6th Street, San Jose, CA 95112 
(408) 288-5565. 

Dealer inquiries invited. 



DECLSMl 
Components 

Dependable service 
at discount prices 

Domestic WSjO } 

and Export 



p 


A A 


„ 




































t 


■ 


" 
■ 


/v vv L 



mini 

Computer Suppliers, Inc. 

25 Chatham Rd., Summit, N.J. 07901 
Since 1973 

(201) 277-6150 Telex 13-6476 



©Mini Computer Suppliers, Inc. 
1979 




goal is to place hardware in- 
to the hands of people who 
will further those educa- 
tional methods that best 
take advantage of the per- 
sonal microcomputer's 
capabilities. 

As continuing evidence of 
its commitment to educa- 
tion, the foundation will 
sponsor the Education Pro- 
gram Information Center 
(EPIC). EPIC will support 
microcomputer users in 
developing new instructional 
programs and in obtaining 
available information on 
educational materials. 
Authors are encouraged to 
submit their work to the 
center for review and feed- 
back on the most effective 
uses and placements of their 
materials. 

Both the Apple Education 
Foundation and EPIC may 
be contacted through the 
Apple Education Founda- 
tion, 20605 Lazaneo Dr, 
Cupertino CA 95014. 



AIDs for Apple Dealers 

AIDs (Apple Independent 
Dealers) was formed by and 
for independent Apple 
dealers, ie: those dealers 
with no direct contractual 
agreement or connection 
with any national chain or 
franchise. AIDs will provide 
a framework for improved 
communication, education, 
and support to its members, 
which will also be of benefit 
to consumers. This will in- 
clude sharing of information 
on new software and hard- 
ware evaluations, successful 
marketing and problem solv- 
ing, advertising ideas and 
more. 

Full membership for 
qualified dealers is $35 per 
year. For more information, 
contact Harry Sweeney, 
(503) 228-5242 or send a 
self-addressed, stamped 
envelope to AIDs, POB 
06126, Portland OR 97206. 



Report Studies Threat to 

Auto Electronics from 

Electric Fields 

With the increased use of 
electronic control systems in 
automobiles, there is con- 



cern about possible malfunc- 
tion or deterioration of 
function due to ambient 
electrical fields created by 
radio and television 
transmitters, high-powered 
radar, power transmission 
lines, or lightning strokes. 

Researchers at the Na- 
tional Telecommunications 
and Information Administra- 
tion (NTIA) have surveyed 
sources emanating energy 
across the radio-frequency 
portion of the elec- 
tromagnetic spectrum. Their 
report indicates that vehicles 
might sometimes — 
although rarely — be expos- 
ed to radio-frequency fields 
of 5 kV per meter which 
may cause the vehicle to 
become inoperative or may 
even damage its electronics. 

The report is available 
from the National Technical 
Information Service, 5285 
Port Royal Rd, Springfield 
VA 22161 for $4.50. The ac- 
cession number is PB 
294-819/AS. For further in- 
formation, contact NTIA 
Office of Congressional and 
Public Affairs (202) 
377-1832. ■ 



BYTE's Bugs 



Correct Reversi 
Termination 

I would like to point out 
a programming error in 
"Reversi," which was 
published in the November 
1979 BYTE, on page 76. The 
problem with the program is 
that it recognizes the end-of- 
game criterion too early, 
allowing the occurrence of a 
player not having a move 
only twice throughout the 
length of the game. This is 
due to the fact that counter- 
variable T3 is never re- 
initialized when a player is 
able to move. I recommend 
insertion of the following 
code: 296 LET T3 = 0. 

Darrell Pittman 

4225 Forest Dr 

Port Arthur TX 77640 ■ 



168 February i960 © BYTE Publications Inc Circle 1 19 on inquiry card. 



By Netronics 

ASCII/BAUDOT, 
STAND ALONE 




COMPLETE 
FOR ONLY . 



Computer $1AQ 
Terminal 1W 



95 



The Netronics ASCII/BAUDOT Computer Terminal Kit is a 
microprocessor-controlled, stand alone keyboard/terminal 
requring no computer memory or software. It allows the use of 
either a 64. or 32 character by 16 line professional display for- 
mat with selectable baud rate, RS232-C or 20 ma. output, full 
cursor control and 75 ohm composite video output. 

The keyboard follows the standard typewriter configuration 
and generates the entire 128 character ASCII upper/lower case 
set with 96 printable characters. Features include onboard 
regulators, selectable parity, shift lock key, alpha lock jumper, 
a drive capability of one TTY load, and the ability to mate 
directly with almost any computer, including the new Ex- 
plorer/85 and ELF products by Netronics. 

The Computer Terminal requires no I/O mapping and 
includes Ik of memory, character generator, 2 key rollover, 
processor controlled cursor control, parallel ASCII/BAUDOT 
to serial conversion and serial to video processing — fully 
crystal controlled for superb accuracy. PC boards are the 
highest quality glass cpoxy for the ultimate in reliability and 
long life. 

VIDEO DISPLAY SPECIFICATIONS 

The heart of the Netronics Computer Terminal is the micro- 
processor-controlled Netronics Video Display Board (VID) 
which allows the terminal to utilize either a parallel ASCII or 
BAUDOT signal source. The VID converts the parallel data to 
serial data which is then formatted to either RS232-C or 20 ma. 
current loop output, which can be connected to the serial I/O 
on your computer or other interface, i.e., Modem. 

When connected to a computer, the computer must echo the 
character received. This data is received by the VID which 
processes the information, converting to data to video suitable 
to be displayed on a TV se't (using an RF modulator) or on a 
video monitor. The VID generates the cursor, horizontal and 
vertical sync pulses and performs the housekeeping relative to 
which character and where it is to be displayed on the screen. 
Video Output: 1.5 P/P into 75 ohm (EIA RS-170) • Baud Rate: 
110 and 300 ASCII • Outputs: RS232-Cor20 ma. current loop 
• ASCII Character Sel: 128 printable characters — 



! , mi , ()*+,-./0123456789: ;<*>? 

WeCOffGHIJKLrlCPQRSTUUyXVZCvr. 
v &C<Jef9hiiklfM0MrstUUM<iZ{i>*l 



BAUDOT Character Set: ABCDEFGHIJKLMNOPQ 
RSTUVWXYZ-?:*3$ti().,90I4!57;2/68» 
Cursor Modes: Home, Backspace, Horizontal Tab, Line Feed, 
Vertical Tab, Carriage Return. Two special cursor sequences 
are provided for absolute and relative X- Y cursor addressing • 
Cursor Control: Erase, End of Line, Erase of Screen, Form 
Feed, Delete • Monitor Operation: 50 or 60Hz (jumper 
selectable. 

Continental U.S.A. Credit Card Buyers Outside Connecticut 

CALL TOLL FREE 800-243-7428 

To Order From Connecticut Or For Technical _— ^ 
T* Assistance, Etc. Call (203) 354-9375 

I Netronics R&D Ltd., Dept. PE-9 
333 Litchfield Road, New Milford, CT 06776 

| Please send the items checked below — 

ID Netronics Stand Alone ASCII Keyboard/Computer 
Terminal Kit, $149.95 plus $3 .00 postage & handling. 
ID Deluxe Steel Cabinet for Netronics Keyboard/Termi- 
nal In Blue/Black Finish, $19.95 plus $2.50 postage 
I and handling. 
□ Video Display Board Kit alone (less keyboard), $89.95 

I plus $3 postage & handling. 
□ 12" Video Monitor (10 MHz bandwidth) fully assem- 
Ibled and tested, $139.95 plus $5 postage and handling. 
□ RF Modulator Kit (to use your TV set for a monitor), 

I $8. 95 postpaid. 
D 5 amp Power Supply Kit In Deluxe Steel Cabinet 
(±8VDC @ 5 amps, plus 6-8 VAC), $39.95 plus $2 
postage & handling. 

I Total Enclosed (Conn. res. add sales tax) $ 
By- 

ID Personal Check □ Cashiers Check/Money Order 
□ Visa □ Master Charge (Bank ft ) 

I Acct. tt . . 

_ Signature 

I Print 



_Exp. Date . 



Name _ 



City. 



u_- 



_Zip 



D Send Me More Information 



-_J 



Start Computing For Just $129.95 With An 
8085-Based Professional Computer Kit— 

Explorer/85 

700% compatible with all 8080 A and 
8085 software & development tools! 

No matter what your future computing plans may 
be, Level "A " — at $129*95 — is your starting point. 

Starting at just $129.95 for a Level "A" operating system, 
you can now build the exact computer you want. Explorer/85 
can be your beginner's system, OEM controller, or IBM- 
formatted 8" disk small business system. . .yet you're never 
forced to spend a penny for a component or feature you don V 
want and you can expand in small, affordable steps! 

Now, for just $129.95, you can own the first level of a fully 
expandable computer with professional capabilities — a com- 
puter which features the advanced Intel 8085 cpu, thereby 
giving you immediate access to all software and development 
tools that exist for both the 8085 and its 8080A predecessor 
(they are 100% software compatible) — a computer which 
features onboard S-100 bus expansion — plus instant conver- 
sion to mass storage disk memory with either 5-1/4" diskettes 
or standard IBM-formatted 8" disks. 

For just $129.95 (plus the cost of a power supply, keyboard/ 
terminal and RF modulator, if you don't have them already), 
Explorer/85 lets you begin computing on a significant level. . . 
applying the principles discussed in leading computer maga- 
zines. . .developing "state of the art" computer solutions for 
both the industrial and leisure environment. 

Level "A" Specifications 

Explorer/85's Level "A" system features the advanced Intel 
8085 cpu, an 8355 ROM with 2k deluxe monitor/operating 
system, and an 8155 ROM-I/O — all on a single motherboard 
with room for RAM/ROM/PROM/EPROM and S-100 ex- 
pansion, plus generous prototyping space. 

(Level "A" makes a perfect OEM controller for industrial 
applications and is available in a special Hex Version which 
can be programmed using 
the Netronics Hex Keypad/ 
Display.) 

PC Board: glass epoxy, plated 
through holes with solder mask 
• I/O: provisions for 25-pin 
(DB25) connector for terminal 
serial I/O, which can also sup- 
port a paper tape reader 
. . . provision for 24-pin DIP 
socket for hex keyboard/dis- 
play . . , cassette tape recorder in- 
put. . .cassette tape recorder output. . .cassette tape control 
output. . .speaker output. . . LED output indicator on SOD 
(serial output) line. . .printer interface (less drivers). . .total of 
four 8-bit plus one 6-bit I/O ports •Crystal Frequency: 6.144 
MHz • Control Switches: reset and user (RST 7.5) 
interrupt. . .additional provisions for RST 5.5, 6.5 and TRAP 
interrupts onboard • Counter/Timer: programmable, 14-bit 
binary • System RAM: 256 bytes located at F800, ideal for 
smaller systems and for use as an isolated stack area in 
expanded systems. . .RAM expandable to 64k via S-100 bus or 
4K on motherboard. 

System Monitor (Terminal Version): 2k bytes of deluxe 
system monitor ROM located at F000 leaving 0000 free for user 
RAM/ROM. Features include tape load with labeling ...tape 
dump with labeling. . .examine/change contents of memory 
. . .insert data. . .warm start. . .examine and change all 
registers. . .single step with register display at each break point, 
a debugging/training feature... go to execution address... 
move blocks of memory from one location to another. . .fill 
blocks of memory with a constant . . . display blocks of memory 
. . .automatic baud rate selection . . variable display line length 
control (1-255 characters/line). . .channelized I/O monitor 
routine with 8-bit parallel output for high speed printer... 
serial console in and console out channel so that monitor can 
communicate with I/O ports. 

System Monitor (Hex Version): Tape load with labeling. . . 
tape dump with labeling . . . examine/change contents of mem- 
ory. ..insert data. ..warm start .. .examine and change all 



By Netronics 




Level "A" at $129.95 is a 
complete operating system, 
perfect for beginners, hob- 
biests, or industrial con- 
troller use. 





Hex Keypad/Display. 




Explorer/85 with 
"C" card cage. 



r&ducT, fipTHEnff" 

eld Road. New Milford, C" 



Netronics 
333 Litchfield 

Please send the items checked below — 
D Explorer/85 Level "A" Kit (ASCII 
Version), $129.95 plus $3 p&h. 

□ Explorer/85 Level "A" Kit (Hex 
Version), $129.95 plus $3 p&h. 

D 8k Microsoft BASIC on cassette 
tape, $64.95 postpaid. 
D 8k Microsoft BASIC in ROM Kit 
(requires Levels "B," "D," and "E"), 
$99.95 plus $2 p&h. 

□ Level "B" (S-100) Kit, $49.95 plus 
$2 p&h. 

D Level "C" (S-100 6-card expander) 

Kit, $39.95 plus $2 p&h. 

D Level "D" (4k RAM) Kit, $69.95 

plus $2 p&h. 

D Level "E" (EPROM/ROM) Kit, 

$5.95 plus 50<r p&h. 

□ Deluxe Steel Cabinet for Explorer/ 
85, $49.95 plus $3 p&h. 

□ ASCII Keyboard/Computer Ter- 
minal Kit (features a full 128 character 
set, upper & lower case, full cursor con- 
trol, 75 ohm video output convertible 
to baudot output, selectable baud rate, 
RS232-C or 20 ma. I/O, 32 or 64 char- 
acter by 16 line formats, and can be 
used with either a CRT monitor or a TV 
set (if you have an RF modulator), 
$149.95 plus $2.50 p&h. 



CT 06676 

plus$2p&!i. 

D Deluxe Steel Cabinet for ASCII 

Keyboard/Terminal, $19.95 plus $2.50 

p&h. 

□ Power Supply Kit ( ± 8 V @ 5 amps) 
in deluxe steel cabinet, $39.95 plus $2 
p&h. 

□ Gold Plated S-100 Bus Connectors, 
$4.85 each, postpaid. 
D RF Modulator Kit (allows you to 
use your TV sel as a monitor), $8.95 
postpaid. 

D 16k RAM Kit (S-i 00 Board expands 
to 64k), $199.95 plus $2 p&h. 
D 32k RAM Kit, $329.95 plus $2 p&h. 

□ 48K RAM Kit, $459.95 plus $2 p&h. 
D 64kRAMKitr$589.95plus$2p&h. 
D 16k RAM Expansion Kit (to expand 
any of the above up to 64k), $139.95 
plus $2 p&h each. 

D Intel 8085 cpu User's Manual, $7.50 
postpaid. 

D Special Computer Grade Cassette 
Tapes, $1.90 each or 3 for $5, postpaid. 
D 12" Video Monitor (10 MHz band- 
width), $139.95 plus $5 p&h. 

□ North Star Double Density Floppy 
Disk Kit (One Drive) for Explorer/ 
85 (includes 3 drive S-100 controller. 



registers. . .single step with register display at each break point 
...go to execution address. Level "A" in the Hex Version 
makes a perfect controller for industrial applications and can 
be programmed using the Netronics Hex Keypad/Display. 

p- Hex Keypad/Display 
Specifications 

Calculator type keypad with 24 
system defined and 16 user 
defined keys. 6 digit calculator 
type display which displays full 
address plus data as well as 
register and status information. 
Level "B" Specifications 

LeveI"B" provides the S-100 signals plus buffers/drivers to 
support up to six S-100 bus boards and includes: address 
decoding for onboard 4k RAM expansion select-able in 
4k blocks. . .address decoding for onboard 8k EPROM expan- 
sion selectable in 8k blocks. . .address and data bus drivers for 
onboard expansion. . .wait state generator (jumper selectable), 
to allow the use of slower memories. . .two separate 5 volt 
regulators. 

Level "C" Specifications 

Level "C" expands Explorer's 
motherboard with a card cage, 
allowing you to plug up to six 
S-100 cards directly into the 
motherboard. Both cage and 
« cards are neatly contained inside 
Explorer's deluxe steel cabinet. 
Level "C" includes a sheet metal superstructure, a 5-card gold 
plated S-100 extension PC board which plugs into the mother- 
board. Just add required number of S-100 connectors 

Level "D" Specifications 

Level "D" provides 4k or RAM, power supply regulation, 
filtering decoupling components and sockets to expand your 
Explorer/85 memory to 4k (plus the original 256 bytes located 
in the 8155A). The static RAM can be located anywhere from 
0000 to EFFF in 4k blocks. 

Level "E" Specifications 

Level "E" adds sockets for 8k of EPROM to use the popular 
Intel 2716 or the Tl 2516. It includes all sockets, power supply 
regulator, heat sink, filtering and decoupling components. 
Sockets may also be used for soon to be available RAM IC's 
(allowing for up to I2k of onboard RAM). 

Order A Coordinated 
Explorer/85 Applications Pak! 

Experimenter's Pak (SAVE $12.50)— Buy Level "A" and Hex 
Keypad/Display for $199.90 and get FREE Intel 8085 user's 
manual plus FREE postage & handling! 

Student Pak (SAVE $24.45)-Buy Level "A," ASCII Key- 
board/Computer Terminal, and Power Supply for $319.85 and 
get FREE RF Modulator plus FREE Intel 8085 user's manual 
plus FREE postage & handling! 

Engineering Pak (SAVE $41.00)— Buy Levels "A," "B," 
"C," "D," and "E" with Power Supply, ASCII Keyboard/ 
Computer Terminal, and six S-100 Bus Connectors for $514.75 
and get 10 FREE computer grade cassette tapes plus FREE 
8085 user's manual plus FREE postage & handling! 
Business Pak (SAVE $89.95)— Buy Explorer/85 Levels "A," 
"B," and "C" (with cabinet), Power Supply, ASCII Key- 
board/Computer Terminal (with cabinet), 16k RAM, 12" 
Video Monitor, North Star 5-1/4" Disk Drive (includes North 
Star BASIC) with power supply and cabinet, all for just 
$1599.40 and get 10 FREE 5-1/4" minidiskettes ($49.95 value) 
plus FREE 8085 user's manual plus FREE postage & handling! 

Continental U.S.A. Credit Card Buyers Outside Connecticut 

CALL TOLL FREE 800-243-7428 

To Order From Connecticut Or For Technical 

Assistance, Etc. Call (203) 354-9375 | 

sonalized disk operating system — just« 
plug it in and you're up and running!), I 
$699.95 plus $5 p&h. 

□ Power Supply Kit for North Starl 
Disk Drive, $39.95 plus $2 p&h. 

□ Deluxe Case for North Star Disk! 
Drive, $39.95 plus $2 p&h . 
D Experimenter's Pak (see above), I 
$199.90 postpaid. 

D Student Pak (see above), S319.8s| 
postpaid. 

D Engineering Pak (see above), I 
$514.75 postpaid. 

D Business Pak (see above), $1599.40 1 
postpaid. 



Total Enclosed $ I 

(Conn. res. add sales tax) By — | 

D Personal Check D M.O. /Cashier's I 
Check □ Visa □ Master Charge | 



(Bank#_ 



Signature _ 
Print 

Name 



_Exp. Date _ 



\ 



City. 



Circle 120 on inquiry card. 



I 

| D Hex Keypad/Display Kit, $69.95 DOS . and extended BASIC with per- State 

Circle 300 on inquiry card. 



_Zip_ 



D Send Me Information 



^J 



BYTE February 1980 169 





DISK EXPANSION PACKAGE 

This package includes everything necessary to 
add disk capabilities to your TRS-80. To buy 
everything in this package would normally cost 
$1100 at your local Radio Shack store. We start 
with the Radio Shack expansion interface and add 
16K RAM. You also receive a Percom 40-track disk 
drive with a dual drive cable. To start you off right, 
we've added the NEWDOS (40-track) disk 
operating system and a box of BASF diskettes. 
Also, the Percom data separator, the component 
which Radio Shack forgot. 
SAVE $181.00 




6 South Street ■ Milford, New Hampshire 03055 -(603) 673-5144 



SMALL BUSINESS PACKAGE 

An ideal starter package for the small business. 
Includes a TRS-80 with 16K RAM and Level II 
BASIC, an expansion interface with an additional 
16K RAM installed, two Percom disk drives-with 
cable and data separator, NEWDOS disk 
operating system (40 track version) and the Cen- 
tronics 730 line printer. 159700 0^ 
SAVE $579.00 ' 



$899.95 



DELUXE EXPANSION PACKAGE 

This package includes a 32K expansion interface 
with the Percom data separator installed, two Per- 
com TFD-100 disk drives and a 4-drive cable, 
NEWDOS+ operating system and 2 boxes of 
BASF diskettes. $1449 95 

SAVE $354.00 





TOLL-FREE 

ORDER 

1-800-258-1790 





LIST 


OUR 


USED 


USED 


TRS-80 COMPUTERS: 


PRICE 


PRICE 


OFFER 


PRICE 


Level-I 4K 


$499 


$449 






Level-I 16K, w/keypad 


$729 


$659 






Level-ll 4K 


$619 


$559 


$350 


$500 


Level-I I 16K 




$669 


$450 


$625 


Level-ll 16K, w/keypad 


$849 


$769 


$475 


$675 


PRINTERS: 










Line Printer III 


$1999 


$1849 






Centronics 779-2 


$1598 


$1095 


$655 


$850 


Line Printer II 


$999 




$545 


$750 


Centronics 730 


$999 


$899 


$545 


$750 


Centronics P1 * 


$499 


$419 


$250 


$358 


Quick Printer II 


$219 


$197 


$100 


$150 


QP-II Exp. Int. Cable 


$20 


$18 






* Cable required 


$39 


$35 







« 



^^ * 5|c COD orders require 
•OC^ 25% cash deposit 

^Pv ^Prices subject to change 
^CPrices do not include shipping 




DELUXE BUSINESS PACKAGE 

Includes all the necessities for a small-to-medium 
size business to become computerized. Includes 
a Level II TRS-80 with 16K RAM installed and 
modified to display upper and lower case letters 
with Electric Pencil, a 32K RAM expansion inter- 
face with the Percom data separator 
installed, three Percom TFD-10 disk drives and a 
4-drive cable, a Centronics 779-2 tractor feed 
printer, a 40-track NEWDOS and Electric Pencil 
Word Processor software. We have even added a 
system desk and printer stand. "t^TOQ Q<> 

SAVE $628.00 




MHKUol.^^—, L|ST 0UR 

EXPANSION INTERFACE: PRICE PRICE OFF 

OK $299 $269 

16K $448 379/403 

32 K $597 479/537 



DISK DRIVES: 

Percom, TFD-100, 40-track 
Percom, dual TFD-100 
Percom, TFD-200, 77-track 
2-drive cable 
4-drive cable 



Radio Shack, 
Radio Shack, 




1, 2, 



ACCESSORIES: 

Telephone Interface 
16K Memory Kit 
16K Memory Kit for E.I. 
RS232-C Interface 
TRS-232 Interface 
Data Dubber 



$499 
$399 



$199 
$99 



$399 
$795 
$675 
$29 
$39 
$469 
$459 



$179 
$99 
$95 
$89 
$49.95 
$49.95 



NO SUBSTITUTIONS ON PACKAGE PRICES 
'Radio Shack and TRS-80 are trademarks of Tandy Corporation. 



USED 


USED 


3FFER 


PRICE 


$165 


$230 


$245 


$340 


$325 


$440 


$290 


$390 


$270 


$370 


$100 


$150 


$55 


$75 



170 BYTE February 1980 



Circle 227 on inquiry card. 



CO 

HI 



CO 

111 

< 



CO 
CO 

HI 

z 

CO 
CD 



NEW SOFTWARE! 



Original ADVENTURE (Microsoft) 

$29.95 

Galactic Empire 16K L II $14.95 

Alien Invasion 16K L II $ 9.95 

Kriegspiei(wargame)16K L II. $7.95 
Oil Baron 16KL II $7.95 



Casino Anthology 16K L II $ 7.95 

TRS-80 Opera Theatre $ 9.95 

Print Spooler (Disk) $24.95 

Floppy Disk Diagnostic (Disk)$24.95 
File Manager 80 $49.95 



COMPLETE IN 
FEBRUARY SOFTSIDE! 

Simulation of flying the United 
States shuttle. The ultimate 
flight simulation! Based on ac- 
tual flight characteristics and in- 
strument display of the space 
shuttle. 



File Manager 80 by Nepenthe. $49.95 32K Disk 
Directory 16K Disk $9.95 

Automated Disk Directory $14.95 32K Disk. Re- 
quires NewDOS. 

Level III BASIC by Microsoft. $49.95 
Level I In Level II by Apparat. Level II, 16K $15.00 
Fortran by Microsoft. 32K - 2 Disks. New low 
price $150.00 (includes macro-assembler.) 

NEWDOS by Apparat $49.95 

NEWDOS + by Apparat $99.95 

Machine Language Monitor by Small Systems 

Software. Level II, 16K $26.95 

Renumber by Lance Micklus. Level II, available 

in 16 through 48K (specify when ordering) $7.95 

Renumber source listing $20.00 



Three Monitors for Disk by Small Systems Soft- 
ware. Disk for 16 through 48K (all in one) $29.95 
KVP Extender by Lance Micklus. Tape - $29.95; 
Disk - $34.95 

KVP 232 by Lance Micklus - KVP adapted for the 
TRS-232. Tape - $29.95 
STB0 Smart Terminal Level II, 16K $49.95 
ST80D Smarter Terminal for disk systems. 
$79.95 

Micro Text Editor by Don Coons. Level II, 4K or 
16K $9.95 

Text-80 by Frank B. Rowlett, Jr. For 32K disk 
systems $59.95 

8080-Z80 Conversion Level II, 16K $14.95 
STAD Trace Monitor 16, 32 and 48K $24.95 



Electric Pencil by Michael Shrayer. Powerful 
machine language word processing system. 
Level II, 16K tape - $100; Disk version - $150 

Spool will print an ASCII file to a parallel line 
printer at the same time you are using your com- 
puter for another program. For 32K Disk 
Systems only. Will NOT work with NEWDOS. 
(2.3 or VTOS 3.0 OK) On cassette $19.95, on Disk 
$24.95. 



TRS-80 Opera Theatre Magnificent sound! by 

Richard Taylor. $9.95 

Challenge Word game with sound. By Richard 

Taylor $9.95 

Oil Baron by Paul Knechtel $7.95 

Galactic Empire by Douglas Carlston $7.95 

Casino Anthology Slot Machine, Stud and Draw 

Poker. $7.95. 

Alien Invasion $9.95 

Concentration by Lance Micklus. Level II, 16K 

$7.95 

Amazin' Mazes by Robert Wallace. Level II, 16K 

$7.95 

Time Bomb by David Bohlke. Level II, 16K $4.95 

Tycoon by David Bohlke. Level II, 16K $7.95 

9 Games for Preschool Children by George 

Blank. Level II, 16K $9.95 

Space Battles by Level IV, Level II, 16K Tape or 

32K Disk, Tape -$14.95, Disk - $19.95 

Star Trek III.4 by Lance Micklus Level II, 16K 

$14.95 



Snake Eggs by Leo Christopherson. With sound 

- Level II, 16K $14.95 

Life Two by Leo Christopherson. With sound 

-Level II, 16K $14.95 

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Circle 121 on inquiry card. 



BYTE February 1980 171 



Technical Fwum 



TRS-80 AUDIO METERING BOX 



Audio Meter for 
Your TRS-80 

David F Miller, 7462 Lawler Ave, Niles IL 60648 



Perhaps I am old-fashioned, but I like to know what is 
happening when I CLOAD or CSAVE a tape on my 
TRS-80. I modified the CTR-41 cassette recorder to allow 
me to hear over its internal speaker what is going in and 
coming out at all times, but that did not tell me enough 
about the levels involved. 

As you have probably discovered, audio levels in and 
out of the cassette port are very important for the suc- 
cessful loading and saving of your hard-fought-for efforts 
on tape. Interpolating the volume control settings of the 
cassette unit on playback can produce a degree of accu- 
racy, but not for tapes received from others. The only 
sure way to understand what is going on is a visual indi- 
cator. The best device would be an oscilloscope, but I 
could not see dedicating my oscilloscope permanently to 
this type of duty. 

The metering circuit shown in figure 1 has proven to be 
adequate for day-to-day monitoring and can be supple- 
mented by the oscilloscope when a difficult tape is en- 
countered. If you have an oscilloscope, look at the ear- 
phone output of the cassette recorder while playing back 
a tape. What you will see is a constant synchronization 




Photo 1: A view of the audio metering box which connects to 
the Radio Shack TRS-80. 



TO 

TRS- 80 
COMPUTER 
AUDIO 
IN 



J 1 

1/8" 

PHONE 

JACK 

(INLINE) 



Dl 

1N34 

GERMANIUM 

DIODE 



v- 



FROM 

CASSETTE 

RECORDER 

"EAR" 

JACK 



PI 
1/8" 
PHONE 
PLUG 



Rl 
47.fl 
1/2W 
— VSv— 



-w- 



Cl 
2.2^F 

35V 



■\t 



Ml 

0-lmA 

METER 



D2 

1N34 

GERMANIUM 

DIODE 



DETECTS NEGATIVE 
GOING PULSES FROM 
CASSETTE MACHINE 



RADIO 

SHACK NUMBER 



CI 272-1407 

Dl 8 D2 276- 1123 

Jl a PI 274-283 

Ml 22-052 OR EQUIVALENT 

Rl 271-009 



Figure 1: Schematic for the TRS-80 audio metering box. The 2 
diodes used must be germanium diodes. 



train of negative pulses occurring at a frequency of 500 
Hz, with negative data pulses popping in and out at 1000 
Hz. (These figures are for Level II. Level I figures are half, 
or 250 Hz and 500 Hz.) 

The metering circuit shown in figure 1 samples these 
negative pulses, rectifies and filters them, and drives the 1 
mA meter movement. With the values shown, the meter 
will read about half scale with the volume on the cassette 
unit set at 5 (normal setting for Level II tapes). To trim 
the meter reading for your individual needs, change the 
value of the electrolytic capacitor across the meter (more 
capacity for a higher reading); this will probably have the 
most noticeable effect. You could also increase or 
decrease the 47 ohm series resistor, but watch for possible 
"loading" effects if you go too low in value (the value 
shown shows no such effects). The diode across the meter 
acts to protect the movement when high levels are en- 
countered (such as during a tape search in fast forward or 
rewind with the "play" button also engaged). Both diodes 
are specified as germanium because there is only 0.3 V 
barrier potential (ie, voltage drop) across a germanium 
type, whereas a silicon diode has 0.7 V drop. 

The earphone jack on the CTR-41, and most other 
recorders, outputs the audio signal from the record 
amplifier when in the record mode, so you will see what 
is CLOADed and what is CSAVEed. 

Photo 1 shows how my unit is packaged. I mounted a 
1/8 inch phone jack on the rear of the plastic meter box 
which accepts the plug to the TRS-80. This jack should be 
insulated from the box if you use a metal enclosure, or 



172 February 1980 © BYTE Publications Inc 



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BYTE February 1980 173 



use an in-line female 1/8 inch phone jack and avoid 
having to keep the jack above possible outside grounds. 
A short shielded cable exits the meter box, terminates in 
an 1/8 inch phone plug, and plugs into the recorder ear 
jack. 

That is all there is to it! If your cassettes are marked 
with the meter readings that are obtained on playback, 
you should be able to load almost anything on the first 
pass. If you see the level on playback begin to drop over a 
period of time, you will know that the tape heads need 
cleaning. I think you will find that this is a useful acces- 
sory. ■ 



Algebraic Identities 
Are Not Numerical 
Identities 



Alan B Forsythe PhD, University of California Los Angeles 
Department of Biomathematics, School of Medicine 
Los Angeles CA 90024 

The development of statistical software can present 
some adverse computational problems. In "Elements of 
Statistical Computation" (January 1979 BYTE, page 182), 
I demonstrated the tip of this iceberg with two algorithms 



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for calculating the standard deviation for some data. The 
first algorithm, the one given in many texts, incorrectly 
gives zero as the answer. The simple modification given 
in that article corrects the defect. This clearly shows the 
fallacy of simply coding the computational procedures 
given in standard textbooks. 

Subsequently, J G Bliss erroneously speculated that a 
division by four rather than five (N-l rather than N) pro- 
bably accounts for the incorrect answer. (See "Statistical 
Computations Recomputed," June 1979 BYTE, page 193.) 
As my original article pointed out, the root of the pro- 
blem is the fact that digital computers have finite preci- 
sion. Algebraic identities are not numerical identities. 
Thus, when very large numbers are added or subtracted, 
the last few digits are lost due to truncation. When faced 
with deviations from large numbers, the user has to be 
very careful with the computational formula employed. 
That is why a better answer can be obtained using the last 
algorithm given in the article. 

A simple example on the TRS-80 is: 

PRINT 1000000 + 1 

The resulting display shows 1E6. That is, one million plus 
one is reported to equal one million. The single-precision 
representation is not adequate for this problem. 

The heart of the computation of the standard deviation 
is the sum of the squares of the deviations about the 
mean. Algebraically this can be deduced from the sum of 
the squares of the individual values and their sum. The 
original article demonstrates that the use of this algebraic 
identity leads to the subtraction of two very large 
numbers and thereby to the loss of the critical digits. The 
computed result for the sum of squares of the deviations 
is zero. It is now clear that if a computationally poor 
procedure yields zero, then it certainly does not matter if 
we divide by five or four. In either case, we still get zero. 

Why is there any question whether to divide by N or 
N — 1 in the calculation of the standard deviation? When 
given the values for the entire population, then divide by 
N; when working with a sample, then divide by N — 1. 
The example in the original article was a sample from a 
much larger population and so the correct divisor of 
N — 1 was used. 

Mr Bliss references an accounting and auditing text- 
book. If, in the auditing situation, in order to verify each 
and every of the thousands of bills paid, then the divisor 
should be N. However, if only a sample was drawn, then 
N — 1 is the appropriate divisor for the standard devia- 
tion. 

Since I am a statistician and not an accountant, I will 
not argue with Mr Bliss about accounting. If his usual 
procedure is to exhaustively study all transactions, rather 
than a sample, then he should divide by N. My experi- 
ence with sampling from large populations has been that 
great economy of effort can be realized without much 
loss in precision with the use of an appropriate sampling 
plan.B 



REFERENCES 

1, Bliss, J F, "Statistical Compulations Recomputed," BYTE, June 
1979, page 193. 

2. Forsythe, A B, "Elements of Statistical Computation," BYTE, 
January 1979, page 182. 



174 February 1980 © BYTE Publications Inc 



Circle 123 on inquiry card. 



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BASIC Formatted Output 



Listing 1 : BASIC source code for the editing routines. Lines 100 to 927 are 
the driver program for the text editor. Lines 9000 to 9997 are the actual 
text editor. The editor is located at a high line number so it may be used with 
many BASIC programs. When using the editor, care must be taken not to use 
any line numbers in your driver program higher than 9000. The editor is 
broken into several routines. Lines 9000 through 9185 define the format that 
will be used. The format statement will be familiar to readers who have 
worked with FORTRAN format statements. Lines 9200 to 9268 parse the 
format statement. The parsed format is stored in arrays V$ and V as de- 
scribed in the text. 

Lines 9300 to 9548 are the free format input routine. The data is entered 
with commas separating the individual units. This routine then takes the data 
and puts it into the desired form. 

Lines 9600 to 9997 take care of formatted output. The format used is a 
table developed by a routine such as that in lines 9200 to 9268. 



I oo 

1 I D 
200 

2 I 
220 
2 30 
240 
250 

2 60 
300 

3 I 
3 20 
330 
3 4 
3 50 
360 
3 70 
375 

3 80 
384 
386 
390 
400 

4 I 
4 20 
4 2 5 
4 3 
44 
4 S Q 
4 6 

4 7 

5 
5 I 
5 2 
5 3 
5 4 
5 5 



REM TEST PROGRAM FOR FORMAT SUBROUTINES 

REM 

DIM V$ ( 30 ) . V( 30 ) . Y( 3 , 30 ) 

E$="ENTER" 



FORMAT" 

FREE FORM" 

FORMATTED" 

STRINGS IN QUOTES 

&. VAR I ABLES " 

INSTRUCTIONS (Y 
N " GOTO 3 7 
PRINT "USE CODE 



1 = " ; G$ 

2 = " ; G $ 

3 = " ; G$ 

4 = INPUT" 
ENTER CODE 



G$ = " 
H$ = " 
I $ = " 
J $=" 

KJ = " 
I NPUT 
IF Y$ 
PR INT 
PR INT 
PR INT 
PR INT 
PR INT 
INPUT 
PR INT 
I F A$ 
I F A$ 
A=VAL( A$ ) 
ON A GOTO 4 00 
PR I NT E$ . G$ 
INPUT F$ 
GOSUB 9060 
PR INT : PR INT 
FOR K= I TO Y9 
PR I NT Y( I . K ) : 
NEXT K 
PR 1 NT 
GOTO 3 70 
PR I NT I: J ; Ci S 



OR N ) : ' ; YS 

FOR FOLLOWING TESTS" 



& TABLE" 
" ; H$ ; K$ 

",!$;" STRING" ; KS 
;G$ ; " . " ; HJ ; " OUTPUT" 
AJ 



G$ 



5 " GOTO 
END" OR 



320 

A$=" E" 



THEN STOP 



500,700,800 



Y ( 2 , K ) : Y ( 3 , K ) 



I NPUT 

PR I NT 
1 NPUT 
GOSUB 
GOSUB 



F$ 

E $ 
ZS 

9 6 
9 4 



H $ ; J $ 



William D Roch 

24000 Bessemer St 

Woodland Hills CA 91367 



Listing 1 continued on page 178 



If your BASIC interpreter has a PRINT 
USING capability, you should have no trou- 
ble printing reports or other similar output. 
If not, then you are at an apparent impasse 
with the standard BASIC output that left- 
justifies everything at fixed positions on a 
line, an approach that has many limitations. 

The routines in listing 1, lines 9000 to 
9997, solve this problem and produce a for- 
matted output. Also included are routines 
for reading an unformatted string and placing 
the fields in numerical or string arrays, and a 
routine forestablishingarraysfor aformatted 
input record. In addition, lines 100 to 927 
are a test program that can be used to get 
the feel of how these routines work. 

Why Format Records? 

There are several advantages to working 
with formatted string records: 

• The position of each field in a record 
is always constant. 

• Only one variable name is needed to 
input, read or print. Counting fields 
when there is more than one record 
type involved is no problem — you need 
only check a record type code and 
break up the record with the proper 
format statement. 

• Records may be created and changed 
with one string type editor rather than 
an individual program or modification 
for each set of records. 

• Most business type applications use 
formatted records. 

Format Definition Routine 

Our primary concern is describing the 
appearance of the record format to the rou- 

Text continued on page 185 



176 February 1980 © BYTE Publications Inc 



Circle 126 on inquiry card. 



What you *C 
is what 
you get! 



C Compiler for CP/M 

New, and available now! An easily affordable compiler 
incorporating most of the features of the full C language. 

BD SOFTWARE 

System requirements: CP/M and at least 24K of RAM 

Variable Types: char, int, unsigned 

Composite Types: arrays, structures, unions 

Pointers: to variables, structures, unions and functions 

Features: is a structured language, all functions (Programs) 
recursive; more powerful expression operators than any 
other von Neumann type language; allows free-formatted 
source; close enough to UNIX"C to make conversions 
feasible. 

Speed: On 2 MHz 8080, the statement 
for (i = 1; i<30000;i++)x = 5; 
takes about 4 seconds to execute. 

Package contains: compiler, linker, library manager; standard 
function library; sample source files include games, a 
terminal emulator with disk I/O plus the source for 
many standard library functions; BDS C User's Guide; 
Book — The C Programming Language by Dennis Ritchie 
and Brian Kernighan of Bell Labs. " Price: $110 

Recipient of the Computer Lib Seal of Approval 

*CP/M is a trademark of Digital Research Corp. 
' 'UNIX is a trademark of Bell Laboratories 



Lifeboat Associates 

2248 Broadway, New York, N.Y. 10024 (212) 580-0082 Telex 668585 



Retro-Graphics™ 



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if ' \ 



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Graphics PC card mounts easily in the Lear 
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Features: 



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Dot Matrix 
Simple Plug-in 
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You will be impressed with the packaging, per- 
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Write or phone today for complete specifications. 

DIGITAL ENGINEERING, INC. 

1775 Tribute Road 

Sacramento, CA 95815 

(916)920-5600 




Circle 127 on inquiry card. 



BYTE February 1980 177 



Circle 128 on inquiry card. 



Bringing Music 
Home 

LET MICRO MUSIC TURN YOUR 

APPLE II INTOA 

FAMILY MUSIC CENTER! 

. Sing along 

. Compose 

. Play 

. Learn from Specialists 




■» 



VISIT THE APPLE DEALER NEAREST YOU 
AND ASK FOR A DEMONSTRATION OF 
MMI'S MUSIC COMPOSER ™ 
The MUSIC COMPOSER is an APPLE II® 

compatible, low-cost music system designed by 
the folks at MMI. Our music software was 
designed by leading experts in music education. 
A simple step-by-step instruction manual leads 
you through entering, displaying, editing, and 
playing music with up to four voices— soprano, 
alto, tenor, and bass. You can change the sound 
of each voice to reed, brass, string, or organ 
sounds and you can even color your own music 
sounds I 

HAVE FUNI THE MUSIC COMPOSER comes 
complete with an instruction manual, software 
disk or cassette — In either Integer or Applesoft 
ROM BASIC, and the MICRO MUSIC DAC music 
card. Just plug the MICRO MUSIC DAC Into the 
APPLE extension slot and connect the audio 
cable to a speaker. 

Suggested retail price J220. 

Ask your local dealer for information on MMI 
music software products, or contact: 





Micro Music inc (30°) 452-6991 

309 Beaufort, University Plaza, Normal, IL 61761 



Listing 7 continued: 



5 60 

5 7 
5 8 

5 90 

6 
6 I 
6 2 
6 3 
64 

6 50 

7 00 
7 I 
7 20 
7 30 
7 4 
7 50 

7 60 
800 

8 I 
8 2 
8 3 
84 
8 5 
8 60 
8 7 
8 7 5 
8 8 

8 9 
900 

9 2 7 
8 9 9 8 

8 9 9 9 

9 00 
900 3 
9 00 6 
900 9 
90 10 
9 12 
90 15 
9 18 
902 1 
902 4 

902 7 
90 3 

903 3 
90 3 6 
9 3 9 

904 
904 ] 
9 04 2 

904 5 
9 04 8 
90 5 1 
9054 

905 7 

905 8 
9060 

906 9 

907 2 
9 7 5 

908 1 
908 4 

908 7 

909 
909 3 
909 6 
909 9 
9 100 
9 10 3 
9 10 6 
9 10 9 
9 112 
9 115 



PR I NT 
FOR K 
PR INT 
NbXT 
PR INT 
FOR K 
PR I NT 
N k X T 
PR I NT 
GOTO 3 70 
PR INT tS 
INPUT 
GOSUB 
PR INI 
INPUT 
GOSUB 
GOTO 



PRINT 
I TO V I 
V$ ( K ) 

PR I NT 
I TO V2 
V( K ) 



;G$ 
FS 
9 60 

PRINT 
Z$ 

9 2 60 
5 60 



STR INGS ' 



NUMBkRS ' 



k $ ; I $ : J S 



J $ 



OUTPUT" :G$ 



NT U$ : PR INT 



FORMAT DEFINITION SUBROUTINk [SUB I/O IA.0 



THIS ROUTINE BRkAKS UP 
STATkMkNT INTO A TABLk 



= " ( A3 



4X 
3 
4 
2 



PR I NT fc$ ; G$ 
INPUT FS 
GOSUB 9060 
PR I NT kj : HJ 
INPUT Z$ 
PR I NT k$ ; " 
INPUT FS 
GOSUB 9060 
GOSUB 9400 
GOSUB 9650 
PRINT: PR 
GOTO 3 70 
REM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 

RkM kXAMPl.t 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
RkM 
V I = I 
V2= I 
V5= I 
Y9= I 

Y( 2 . 1 ) = 1 
W$= " " 

U S = * A I F X .)." 
KOR V7 = 2 TO l.EN( KJ ) 
X$=MI D$ ( F$ . V7 , I ) 
FOR V8= I TO 8 
IF X$=MI DJ ( US . V8 . I ) 
NkXT V8 

IF X$>="0 " AND X$<= " 9 " 
PRINT •FORMAT kRROR (" 
STOP 

IF V8 <5 GOTO 9 12 1 
V8 =V8 - 4 



F$ 
A3 
4X 

2 F7 
X 

3 I 6 

INPUT 

FS 
OUTPUT : 

V I 

V2 

Y( 1 .K) 

Y( 2 ,K) 

Y( 3 ,K) 

Y9 
VAR I ABkk 



A FORTRAN' TYPk FORMAT 
FOR USE WITH [SUB 1B.IC, 

6 ) " 



ID] 



2 F 7 . 2 . X . 3 

CHAR STRING ( 3A - BAD kNTRY) 

BkANKS (4X6 - 6 IGNORkD) 

REAL NOS OF 7 CHARS W/ 2 

BkANK 

INTkGkRS 6 CHAR LONG 



FORMAT 

D IM AS RkQU I RED 

- STR I NG F I ELD COUNT 

- NUMBER FIELD COUNT 
) - TYPE l=STRING. 2=1NTEGER. 3=REAL. 
) - FIELD START POSITION IN INPUT OR 
) - LkNGTH OF FIELD 

- NO OF FIELDS INCLUDING BLANKS + I 
NAMES USED: 



DECIMAL PLACES 



4=BLANK 
OUTPUT RECORD 



F$.U$.W$.X$.VI,V2,V3.V4,V5,V6.V7.V8.V9.Y(I.K).Y9 



GOTO 9 112 



GOTO 9 142 

X$ ; " ) " 



Listing 1 continued on page 180 



178 February 1980 © BYTE Publications Inc 



Circle 129 on inquiry card. 



Circle 130 on inquiry card. 



MIEAU 



OSBORNE 
BUSINESS SOFTWARE 

in CBASIC2 or CROMEMCO 16K BASIC 



* features * 
Four Complete Packages—- 

• General Ledger 

• Accounts Receivable 

• Accounts Payable 

■ Payroll with Cost Accounting 
Strong support from Osborne Manuals 
CBASIC2 runs under CP/M or under CDOS 
version 1.07 on Cromcmco computers 
16K BASIC runs on Cromemco computers 
Cursor addressing routines for Hazeltine, 
Lear Siegler and Cromemco (Beehive) 
Terminals 

Source Codes and Installation Instructions 
provided along with disks 
Automatic Command Start-up 
Easy to apply to all of your business and 
systems needs 



• hardware required * 

• One or more 8" or 5" Floppy 
Drives 

• CRT with cursor addressing 

• 132-Column Printer 



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package 



CREDIT CARDS MCEt'HD 



i DEALER INQUIRIES INVITED. 





MICMH'S PRODUCTS Of DISTINCT 


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I . DUP/3 lDOP/2 Expanded] 


• DKivi (Customlied 


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Formal Utility! 


■ DBMS Conversion lo NAD 



* Call or Write for Free Catalogue and More Information • 
• We will Customize any of our programs at our Standard Consulting Rates 



Ah! MICAti 



.Satisfyin' Software 



That turns your system on! 

MICro Applications and Hardware 

. CONSULTANTS and SOFTWARE DEVELOPERS . 

i MICAH Box 22212 San Francisco, California 94122 USA phone: 415/664-0778 . 



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Good programming deserves good documentation. BITS Inc. 
has developed a programming form to help assembly language 
programmers write and preserve their programs in a loose-leaf 
notebook format. BITS PROGRAMMER PADS™ are now available 
for the 8080A, Z-80, 1802, 6800, and 6502 microprocessors. 
On one side of the form the processor's register architecture is 
laid out along with continuous memory locations. This allows the 
details of your program's register use, stack manipulations, in- 
dexed addressing, and table and data storage to be permanently 
recorded. The other side is for your program or subroutine listing. 
Its source listing is entered in the instructions, labels and com- 
ments columns. Assembling is done next by filling in the object 




code column which is wide enough for two or three byte instruc- 
tions. Memory locations are assigned in the address column. If 
revision or relocation of the program is necessary, the address col- 
umn can be renewed using typewriter correction tape (a white 
paper tape about 1/3" wide) and memory addresses reassigned. 
BITS PROGRAMMER PADS will protect the effort you have put 
into your programs and take some of the pain out of hand 
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inc Books to erose the impossible 25 Route 101 West, PO Box 428, Peterborough, NH 03458 



1B020 



BYTE February 1980 179 



Circle 132 on inquiry card. 




AND 
STUFF 





Computer terminals, business systems, 
lab components . . . they all need desks 
and enclosures. That's what we're all 
about. Computer Furniture and Acces- 
sories offers a standard line of furniture 
suitable for a wide variety of applica- 
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furniture in all shapes, sizes and colors. 
Basic models shipped from stock in 
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ask for? 



CF*A 



Computer Furniture and 

Accessories, Inc. 

1441 West 132nd Street 

Gardena, CA 90249 

(213) 327-7710 



180 February 1980 © BYTE Publicalions Inc 



Listing 7 continued: 



9 118 

9 i : i 

9 13 
9 13 3 
9 13 6 

9 119 
9 14 2 
9 14 5 
9 148 
9 15 1 
9 15 3 
9 15 4 
9 15 7 
9 16 
9 16 1 
9 16 5 
9 16 6 
9 16 9 
9 17 
9 17! 
9 17 2 
9 17 5 
9 17 8 
9 18 1 
9 18 4 
9 18 5 
9 19 
9 19 2 
9 2 
9 2 3 
9 2 6 
9 2 9 
9 2 12 
9 2 15 
9 2 18 
9 2 19 
9 2 2 1 
9 2 2 4 
9 2 2 7 
9 2 3 
9 2 3 3 
9 2 3 6 
9 2 3 9 
9 2 4 2 
9 2 4 5 
9 2 4 8 
9 2 5 1 
9 2 5 4 
9 2 6 
9 2 6 6 
92 69 
9 2 7 2 
9 2 7 5 
9 2 7 8 
9 2 8 1 
9 2 8 4 
9 2 8 7 
9 2 9 
9 2 9 3 
9 2 9 6 
9 2 9 7 
9 2 9 8 
9 3 
9 3 3 
9 3 6 
9 3 9 
9 3 12 
9 3 15 
9 3 16 
9 3 18 
9 3 2 1 
9 3 2 4 
9 3 2 7 



GOTO 9 13 9 

V 9 = V 8 

V 6 = V 6 + I 

IF V6 = 2 THEN V5 =VAL (WS ) 

GUI (> 9 18 1 
II- VI <> 4 GOTO 9 15 1 

w$ =w$+x$ 

V6= I 

GOTO 9 18 4 
V4-VAL ( W$ ) 

I I- V 5 = THEN V 5 = I 
II- V 9 = 4 r HEN V 4 = V 5 
IF V9 = 4 THEN V5 = I 
FOR V3 = 1 TO V5 

Y ( I . Y 9 ) = V 9 

Y ( 3 . Y 9 ) = V 4 

Y(2.Y9+I )=INT(Y(2.Y9)+V4) 
Y9 =Y9+ I 



V7 



II- V 9 = 2 
IK V 9 = I 
N E XT V 3 
V5 = I 
V6= I 
WS = " " 
N I: X I 
RETURN 
R EM 
RLM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 
REM 



OR V 9 = 3 
THEN V I : 



T li E N 

v i + I 



BREAKS UP A EORMATTED STRING SUBROUTINE 



SUB 



/O 1 B . ] 



I NTO 
I NTP 



SUBROUTINE BREAKS UP A FORMATTED STRING RECORD FROM: 
READ FROM INPUT STATEMENT 
READ FROM DATA STATEMENT 

FORMATTED INPUT ■ STRING MUST BE IN QUOTES (") 
INPUT STATEMENT USING BASIC PATCHED FOR USE 
WITH ROCHE MULT I -CASSETTE CONTROLLER 
STRING AND NUMBER ARRAYS BASED ON A TABLE BUILT 
THE PROGRAM OR FROM PARAMETERS CREATED BY [I/O IA.0] 



I ) 



I NPUT 

Z$ 

Y( K 

Y9 
REM OUTPUT: 
REM V$ ( I ) 
REM V( I ) 
REM VARIABLE 
REM V$ ( I ) , 

V I =0 
V2 = 

FOR V 7 = I TO Y9- 
ON Y ( I , V7 ) GOTO 

V I =V I + I 

V J ( V I ) =M1 D$ ( Z$ . Y( 2 
GOTO 9 2 90 

V 2 = V 2 + I 

V ( V2 ) =VAL ( M I DS ( Z% . 

NEXT V7 

Z $ « " " 

RETURN 

REM 

RIM 

RIM 

REM 

REM 

RLM 

REM 

RLM 

REM 

RLM 

RLM 

REM 

REM 



INPUT STRING 

PARAMETER TABLE 

NO OF FIELDS INCLUDING 



BLANK FIELDS 



- STR I NG F I ELD 

- NUMBER FIELD 
NAMES USED: 

ZS ,V( I ) , VI , V2 , 



ARRAY 
ARRAY 



V7 . Y( I , K) , Y9 



9275,9284,9284,9290 



V7 ) . INT( Y( 3 , V7 ) ) ) 



Y( 2 . V7 ) , INT( Y ( 3 , V7 ) ) ) ) 



FREE FORM INPUT SUBROUTINE |SUB I/O ICO] 

THIS ROUTINE ACCEPTS A FREE FORM INPUT STRING AND PRO- 
DUCES A STRING AND/OR NUMBER ARRAY BASED ON A TABLE BUILT 
INTO THE PROGRAM OR CREATED BY [SUB I/O I A ] . 
BLANKS ARE USED AS DELIMITERS BETWEEN FIELDS. 
SIRING FIELDS CONTAINING BLANKS OR WITH 
LEADING OR TRAILING BLANKS MUST BE 

ENCLOSED WITH A DELIMITER. NUMERIC FIELDS ARE 
EDITED FOR NON-NUMERIC CHARACTERS. IF THE INPUT 
STRING HAS TOO MANY FIELDS THE EXTRA FIELDS WILL 



Listing 1 continued on page 182 



Circle 133 on inquiry card. 

APPL6 COMPUT€fl™ IFfl SIMULATOR 
NOW YOUR flPPl€ CRN FLV! 

The latest version of Aircraft flight simulator 
includes duel navigation radios and allows 
the pilot to actually flu instrument landings 
using IIS and Glide slope. 

After the approach, a plot is presented 
shoaiing the flight path. 

This one program gives your Apple™ more 
flight simulator power than most $10,000 
machines on the market today, AND FOR ONLV 
$19.95. 

Available from 

Programmers Software exchange 

Box 199 

Cabot Arkansas 72023. 

(501) 843-6037 



Circle 134 on inquiry card. 



NO FRILLS! NO GIMMICKS! JUST GREAT 

DISCOUNTS 

MAIL ORDER ONLY 



HAZELTINE 

1400 ) 

1410 Call 

1420 I For 

1500 .. . Prices 

1500(Kit) .... / 

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700-2 1350.00 

703 tractor 2195.00 

Micro Printer 395.00 

730 975.00 

NORTHSTAR 
Horizon I assembled. . 1629.00 

kit 1339.00 

Horizon II assembled. . 1999.00 

kit 1599.00 

TELETYPE 

Mod 43 995.00 

INTERTEC 
Superbrain 2195.00 



DIGITAL SYSTEMS 

Computer $4345.00 

Double Density 
Dual Drive 2433.00 

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912 ... 1 Call 

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810 Printer 1595.00 

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ADDS Regent 25 CALL 

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5" Scotch Diskette .... Box/29.95 
8" Scotch Diskette .... Box/34.95 



Most items in stock for immediate delivery. Factory-fresh, sealed cartons. 

DATA DISCOUNT CENTER 

Box 100 135-53 Northern Blvd., Flushing, New York 11354, 212/465-6609 

N.Y.S. residents add appropriate Sales Tax. Shipping FOB N.Y. 
I BankAmericard, Master Charge add 3%. COD orders require 25% deposit. 



SAVE THE WHALE 

The Fm Whale is the world's greatest long-distance communicator. 



Scientists believe that loud, deep-tone, low-frequency 
sounds made by Fin Whales (frequencies around 20 
hertz, or cycles per second) actually travel 
underwater for distances of at least 500 
miles, and under optimum conditions 
might carry for a radius of over 
4,000 miles, potentially reach- 
ing an area greater than the v .> 
entire Atlantic Ocean. 



ng by 
Sinrti 





Fin Whales, the secon 

creatures ever to have lived 

earth, grow up to 24 meters in length ( 

ceeded only by the 30-meter Blue Whale) 

abit all the oceans of the world. Tens of th 

Fin Whales have been "harvested" in recent years, 

of the International Whaling Commission, for the sa 

for which substitutes are readily available. 



ex- 

and 
ousands of 
by agreement 
e of products 



The CONNECTICUT CETACEAN SOCIETY is a small, totally volunteer, non-profit edu- 
cation and conservation organization dedicated to seeking the abolition of all whale killing. Any 
concerned citizen can help our efforts by sending name and address and a $15 or more contribution 
to: CCS, P. O. Box 145, Wethersfield CT 06109. 



Circle 135 on inquiry card. 



BYTE February 1980 181 



Circle 136 on inquiry card. 



SENSATION! 



You have been reading about our astounding 
high performance microcomputer products. 
Our X-9000 Pascal MICROENGINE"'* CPU that 
executes Pascal 1 3x faster than an LSI-1 1 
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Our X-8000 16-bit CPU addresses 8M bytes 
of memory directly and is coming soon! 

"Trademark Weslern Digital Corporation 



DISPLAY/EDIT TERMINAL 
Model X-920 




$920 

S 820 (Without 18 function keys) 



STANDARD FEATURES (partial list) 

• Microprocessor controlled 

• Serial RS232C and 20 ma current loop 

• 10 baud rates— 75 to 19,200 

• 24 lines x 80 characters 

• 96 ASCII displayable characters 

• Upper and lower case 

• 12 x 10 character resolution 

• Dual intensity display 

• Clear full intensity data only 

• Programmable reverse video 

• Programmable underline 

• 105 keys with alpha lock 

• 14 key numeric pad with decimal 

• 16 special function keys 

• 8 edit function keys 

• 2 block transmission keys 

• Self test mode 

• Protect mode 

• Block mode 

• 80 storable tabbing 

• Insert/delete character and line 

• Scrolling 

• Addressable cursor 

• A host of other features, including cursor controls 
and remote commands such as clear to nulls, 
spaces, end of line, end of screen; set hi, lo, zero 
intensity; set blink; etc. 

• Optional screen print & 2nd page memory 

For our system or for yours, in commercial, 
technical, educational or personal applications, 
the Computex X-920 Is unmatched in its class. 



All features of the Hazeltine 1400 and ADM-3A 

Plus: 128 ASCII characters . . . 

7x10 matrix . . . Reverse 

video. . . Print key. . . 

Shiftlock . . . Transparent 

mode . . . Backspace . . . 

Tabbing... Integrated 

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List price S 9 5 6 

PERKIN-ELMER (Model 550) 



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Full refund with the return of any product 
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5710 Drexel Avenue 
Chicago, IL 60637 



Listing i continued: 



9 3 3 o 

9 .i 3 i 

9 3 .1 6 

9 3 .1 9 

9 3 4 2 

9 .1 4 5 

9 3 4 8 

9 3 5 1 

9 3 5 4 

9 3 5 7 

9 3 6 

9 3 69 

9 3 7 2 

9 3 7 5 

9 3 7 6 

9 3 7 8 

9 3 8 1 

94 00 
940 3 

9 40 6 

9 409 

9 4 12 

9 4 15 

9 4 16 

9 4 18 

9 4 2 1 

9 4 2 4 

9 4 2 7 

9 4 3 

9 4 3 3 

94 3 4 

94 3 5 

9 4 3 6 

9 4 3 9 
944 2 

9 4 4 5 

9 4 4 8 

9 4 5 1 

9 4 5 4 

9 4 5 7 

9 4 6 

9 4 6 3 

9 4 6 6 

9 4 6 9 

9 4 7 2 

9 4 7 5 

9 4 7 8 

9 4 8 1 

9 4 8 4 

9 4 8 7 

9 490 

9 4 9 3 

9 49 4 

9 4 9 6 

9 4 9 9 

9 5 

9 5 3 

9 5 06 

9 5 9 

9 5 12 

9 5 15 

9 5 18 

9 5 2 1 

9 5 2 4 

9 5 2 7 

9 5 3 

9 5 3 3 

9 5 3 6 

9 5 3 9 

9 54 2 

9 54 5 

9 5 4 8 

9 6 00 



RbM 
Rl-.M 
RfcM 
RbM 
RLM 
RLM 
RLM 
RLM 
RLM 
RLM 
RLM 



BE IGNORED. 

IK THE INPUT STRING HAS TOO LEW K1ELDS THE EXTRA 
FIELDS WILL BL 'BLANKED' OR ZEROED'. FOR 
BLANK FIELDS - ENTER '0' FOR NUMERIC AND ONE BLANK 
ENCLOSED BY DELIMITERS FOR STRINGS. 



INPUT 
Z$ 
Y( I 
Y9 
DS 



RLM OUTPUT 



RLM 
RLM 
RLM 
RLM 
RLM 
FOR 



V$ ( I ) 
VII) 
ERR 
VARIABLE 



TO V2 



DELIMITER MAY BE USED 



D$ . V$ ( I ) 
V 3 = 1 TO V I 

V J ( V 3 ) = " " 
NEXT V3 
FOR V3= I 
V ( V 3 | = 
NEXT V 3 
REM ANY 
DS-"#* 

V I =0 
V2=0 
V4= 1 
V5=0 
V6= I 
WS = " " 
ERR= I 

FOR V 7 = I TO LEN( Z$ ) 

IF Y(I.V6)<>4 GOTO 9 4 4 8 

V6=V6+ I 

GOTO 9439 

X$=MID$(Z$.V7.I) 

IF XIODI GOTO 9 4 6 9 

V 4 = V 4 + I 

IF V7=LLN ( ZS I GOTO 9 5 15 
IF V4 = 2 GOTO 9 5 4 5 
V4 » I 

GOTO 9 545 

II- X$ = " " GOTO 9 5 3 
V3 = I 

I I Y ( I . V6 ) = I GOTO 9 4 9 3 

II XS>= " " AND X $<= " 9 " 
IF X$= " • " GOTO 94 9 3 

IF X $ = " . " AND Y ( I . V 6 ) = 3 



- INPUT STRING 

• PARAMETER TABLE 

- NO OF FIELDS INCLUDING BLANKS + I 

- DLL IM I TER 

- STRING FIELDS ARRAY 

- NUMERIC FIELDS ARRAY 

- I -OK , 2 - ERROR 
NAMES USED: 

W$.X$.V(I).VI,V2,V3,V4,V5.V6.V7.Y9 



GOTO 94 9 3 



V6 



GOTO 949 3 
) NOT NUMERIC" 



PR I NT " F I L ID ( 
LRR=2 : RETURN 

V 5 = V 5 + I 

IF V5> I NT( Y( 3 . V6 ) ) GOTO 9 54 5 
WJ=W$+X J 

IF V7=LEN(Z$) GOTO 95 12 
GOTO 9 5 4 5 

IF V4 = 2 GOTO 94 9 3 

IF V3=2 GOTO 9 5 12 

V 3 = 2 

IF Y ( I . V6 I <> I GOTO 9 5 2 4 

V I =V I + I 
V$ ( V I ) =w$ 
GOTO 9 5 3 
V2 =V2+ I 

V( V2 ) =VAL ( W$ ) 
V6=V6+ I 

IF V7=LEN( Z$ ) GOTO 9 54 8 
V5 =0 
W$ = " " 

IF V6=Y9 GOTO 9 5 4 8 
NEXT V7 
RETURN 
REM FORMATTED OUTPUT SUBROUTINE 



SUB I/O I D . ] 

Listing 1 continued on page 184 



182 February 1980 © BYTE Publications Inc 



Circle 137 on inquiry card. 



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Listing J continued: 



9 60 3 
9 60 6 
9 60 9 
9 6 12 
9 6 14 
9 6 16 
9 6 18 
9 6 2 1 
9 6 2 2 
9 6 2 4 
9 6 2 7 
9 6 3 
9 6 3 3 
9 6 3 6 
9 6 3 9 
9 642 
9 64 5 
9 64 8 
9 64 9 
9 6 5 
9 6 5 2 
9 6 5 4 
9 6 5 6 
9 65 8 
9 6 60 
9 66 3 
9 6 66 
9 66 8 
9 669 
9 6 7 1 
9 67 2 
9 6 7 5 
9 67 8 
9 6 8 1 
9 6 8 4 



REM 
REM 
REM 
RbM 
RUM 
RbM 



POS I T ION 
ZEROS ARE 



INPUT: 

VS ( I ) 

V( I ) 

Y( 1 . K ) 

Y9 
OUTPUT : 

U$ 
VAR I ABLb 



- STR I NG FIELD ARRAY 

- NUMBER F I ELD ARRAY 
PARAMETER TABLE 

- NO OF FIELDS INCLUDING 

- OUTPUT STRING RECORD 
NAMES USED 



BLANKS + I 



THIS ROUTINE ACCEPTS ARRAYS OF STRING AND NUMBER 
FIELDS AND PRODUCES A FORMATTED STRING RECORD 
BASED ON A TABLE BUILT INTO THE PROGRAM OR CREATED 
BY |SUB A/O TABLE BUILD PROGRAM]. 
NUMBERS ARE RIGHT JUSTIFIED. DECIMAL 

REM OF REAL NUMBERS ARE HELD AND TRAILING 

REM ADDED IF REQUIRED. 

REM 

RbM 

REM 

REM 

REM 

REM 

REM 

REM 

REM 

REM 

REM 

U $ = " " 

V I =0 
V2 = 
FOR V9= 1 

w$ = - " 

V5=Y( I . V9 ) 

V3= INT( Y( 3 . V9 ) ) 

ON V 5 GOTO 9668.9689.9689.9669 

V I =V I + I 

FOR VB= I TO V3 
IF V5<> I GOTO 967 5 

Y$=M1 D$ ( VS ( V 1 ) . V8 . 1 ) 

IF Y$="" OR V5=4 THEN Y5=" " 

IF V5=2 OR V5=3 THEN ¥$»"•" 
W$=W$+Y % 
NEXT V8 



U$.V$( I ).W$.Y$,V( I ) .VI ,V2.V3.V4.V5.V6.V7.V8.V9.Y( 1 . K ) .Y9 



TO Y9 - I 



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184 February 1980 © BYTE Publications Inc 



Circle 139 on inquiry card. 



Listing 7 continued: 



THEN V7= V7+ I 
" THEN V7=V7 - I 

GOTO 9 7 1 
9 7 1 



Y$=MI D$ ( Y$ , 2 ) 



9 68 5 US=US+WS 

9 68 7 GOTO 9 7 6 

9 6 8 9 V 2 » V 2 + I 

9 6 9 V7= I NT ( V ( V2 ) ) 

9 69 .1 V7 = 1.EN ( SIRS ( V 7 ) ) • I 

9 6 9 4 Y S = S T R S 1 V ( V 2 ) 

9 69 6 II- II- KTS ( YS . I 

9697 IK MIDSIYS .1 , 

9 6 9 8 II II-. I IS ( Y$ . I 

9699 I f V ( V 2 ) > I . I) GOTO 

9 7 V 7 = . 

9 7 1 IK I.EKTS ( YS . I )<> " - " THEN 

97 0.1 V4=(Y(.1.V9) - I0).(V3«I0) 

9 7 6 IK V 5 = 3 GOTO 9 7 2 1 

9 708 IK V3 - l.l:N( Y$ ) =0 GOTO 97 16 

9 709 KOR V8=l TO V.l-EEN(YS) 

9 7 12 W$=W$+ " " 

9 7 15 NEXT V8 

9 7 16 WS=W$+Y$ 

9 7 18 GOTO 9 7 5 7 

9721 IK V7-t>- V3-V4 GOTO 96 69 

9724 IK I NT ( V ( V2 ) ) =V ( V2 ) THEN Y$=Y$+" 

9 7 2 7 V 6 = 

9728 V7=V4+V7+I 

9729 V 7 = V J - V 7 

9 7 J I KOR V8= I TO VJ 

9 7.1.1 IF I NT ( V7+ . 00 5 ) > ( V8 - I ) GOTO 9748 

97. 16 V 6 = V 6 + I 

9 7 .1 9 V$=M I D$ < YS . V6 . I ) 

9 74 2 IK V$ = "~ THEN V$="0" 

9 7 4.1 W$=W$+V$ 

9 7 45 GOTO 9 7 54 

9 74 8 W$=W$+" " 

9 7 5 4 NEXT V8 

9757 U$=U$+W$ 

9 7 60 NEXT V9 

9 7 6.1 RETURN 

9 9 9 7 END 



Text continued from page 176: 

tine. This is done with a FORTRAN type 
format statement which defines: 

A = Alphabetic or String Field. 

I = Integer Number. 

F = Floating Point or Real Number. 

X = Blank. 

Table 1 shows how these formats are used. 

The format definition routine takes the 
format string statement (F$) and converts it 
into a 3 column array (V). The first column 
defines the type of field: string, alphanu- 
meric, integer, real, or blank. The second 
column provides the starting position of the 
field within the record. The third field pro- 
vides the length of the field and number of 
decimal positions. This routine creates a 
parameter table that is used by the other 
routines. 

The parameter table could also be built 
using values from DATA statements read into 
the proper variables thus eliminating the table 
build routine. Once the table is created, it can 
be used with INPUT, READ and PRINT 



Copies of these routines are available for $5 on 
paper tape or Tarbell format cassettes for 8 K 
V3.1, 3.2 and 4.0 BASIC from Elliam Associates, 
24000 Bessemer St, Woodland Hills CA 91367. 



Record Description 










Product Class 




A2 






Product Code 




A6 






Description 




A15 






Vendor Code 




13 






Quantity On Order 




14 






Quantity On Hand 




14 






Sold Year To Date 




14 






Unit Sales Price 




F7.2 






Format Statement 










F$="(A2,A6,A1 5*13,3 14, F 7.2)" 










Data Record 








TWHD1 10V Tape Winder 


107 


45 37 


123 


27.00 




• — . — ■ 


— . — ' — . — 


- — , — - 


- — . — - 


V$(1)V$(2) V$(3) 


V(1) 


V(2) V(3) 


V(4) 


V(5) 



statements to convert the input or output 
string into string and number array variables. 
Any number of formats may be used in a 
program, but the format definition routine 
must be rerun each time a different format is 
used. 

Fixed Form Input 

The normal action of BASIC requires an 
entry for each field listed as a variable with 
an INPUT statement. This is a nuisance when 
you have an input and output (IO) field 
record and the last five entries are blank 
most of the time. The fixed form input does 
not require that the trailing fields be 
entered, since they will be blanked or zero 
filled. It is sometimes easier to keep the 
keyed input in neat columns (fixed format) 
rather than following one field after another 
(normal BASIC). 

Example: 

Normal BASIC 

14,16,98 

1457,258,7 

2,3,7 

Fixed Format 

14 16 98 

1457 258 7 

2 3 7 

The main advantage is in inputting for- 
matted records from cassette tape or floppy 
disk. (See formatted output section, para- 



Table J: Format statement 
and corresponding data 
record. The descriptions 
for formats used here are 
FORTRAN types. The 
product class is an alpha- 
numeric quantity having 
two characters, the prod- 
uct code consists of six 
alphanumeric characters 
and the description of 1 5 
characters. The particular 
vendor code is a 3 digit in- 
teger. The quantity on 
order, on hand and the 
number sold up to this 
date are all 4 digit integers. 
The unit sales price is a 
7 digit floating point num- 
ber with two digits after 
the decimal place and four 
digits before the decimal 
place. 



February 1980 © BYTE Publications Inc 185 



graph after next, for further discussion of 
external 10.) 

Free Form Input 

Now that formatted input has been pre- 
sented, let's look at the advantages and dis- 
advantages of free form input. The major 
advantage is that data fields need only be 
separated by a blank and the routine will 
reformat that field to its proper place in the 
input record. Strings and numbers may be 
intermixed, but strings containing leading 
blanks or blanks within the string must be 
enclosed with a delimiter. The routine de- 
limiter is a pound sign (#), although any 
character might be used. Blank fields must 
also be enclosed with delimiters, and nu- 
meric fields require a zero. Each method has 
its advantages and drawbacks depending on 
the type of data being handled. An example 
is shown in table 2. 



Table 2: In this example a free form Input is read by a formatting routine and 
stored on a record as indicated. 



Example: 

keyed input 

format 

record 



TW HD110V #TAPE WINDER #107 45 123 27.0 
F$=" (A2,A6,A15,I3,3I4,F7.2)" 
TWHD100VTAPE WINDER 107 45 123 27.00 



Table 3: Examples of how the format will affect the data that is being output. 
Note that some of the resulting output formats are indented. This is a result 
of leading blanks created to satisfy the format requirements for certain cases. 



Data Format 


Format Statement 


Output Format 


ABCDE 


A6 


ABCDE 


ABCDEFG 


A6 


ABCDEF 


123 


14 


123 


12345 


14 


* # # * 


12.34 


F6.2 


12.34 


12.3475 


F6.2 


12.35 


12. 


F6.2 


12.00 


11234.1 


F6.2 


****** 



Formatted Output 

The formatted output routine uses the 
parameter table values and the variable array 
values in the V array and places them in the 
output string. Blanks as called out in the 
format statement are included. Strings are 
left justified (start in the first position of the 
field) and numeric values are right justified 
(any spaces appear on the left). Numeric 
values larger than the field call out cause the 
field to be filled with asterisks. Floating 
point (real) numbers with fewer than the 
required decimal places are zero filled. Num- 
bers with more decimal places than the for- 
mat allows are rounded as shown in table 3. 
Taking table 2 as an example input, the data 
could be printed with a different format 
such as in table 4. 

About the Routines 

The line numbers used by these routines 
are set high (above location 9000 in memory) 
so that BASIC programs can be written 
under them. Care must be taken that your 
programs do not have line numbers higher 
than 9000. All of the variable names used in 
each routine are listed in the comments. 
These variable names must not be used in 
your programs. All the comments are 
included before the routines so they may 
be deleted to save space. 

More About Records 

Obviously, it takes only a minimum 
amount of extra code to switch fields, add 
string constants and perform mathematical 
functions. Using the input data record of 
table 1, the transformations in table 5 may 
be made. 

Once these routines are in your library, it 
is a simple matter to load them into memory, 
to key in your program and to add format 
statements." 



Table 4: Format and ex- 
ample output using the 
format and the data in 
table 3. 



Table 5: Some typical transformations that may be performed on the stored 
and formatted data. The last line is the result of these transformations using 
the given format. 



F$="(A2,X,A6,X,A1 5,13,3 I5,F8. 3)" 

TW HD100V Tape Winder 107 45 37 123 27.00 



V$(1)="Retail Value O/H" 




change a string 


V$(2)=V$(3) 




move a string 


V(1)=V(3)*V(5) 




calculate a value 


F$="(A16,2X,A15,F8.2)" 




format 


Retail Value O/H Tape Winder 


199.00 


output record 



186 February 1980 © BYTE Publications Inc 



Circle 140 on inquiry card. 



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BYTE February 1980 



187 



Beck Reviews 



Let's Talk LISP 



by Laurent Siklossy 
Prentice-Hall, 
Englewood Cliffs N] 1976 
237 pages hardcover 
$14.20 

Let's Talk LISP is a fun 
and useful book to read, at 
least for those of us who 
learn best when the material 
is presented in an interesting 
way. This is especially 
helpful for LISP, because for 
someone who is familiar 
with traditional program- 
ming languages, LISP seems 
very peculiar at first. After 
reading Let's Talk LISP and 
writing a few programs, I 
wondered how I had man- 
aged to avoid LISP for so 
long. 

The structure of the book 
is extremely straightforward. 



The first two chapters intro- 
duce the fundamental 
building blocks of LISP. 
After that, the reader is led 
through function definitions, 
recursion, MAP functions, 
and assorted elements of the 
language. Midway through 
the book, the author 
demonstrates how to write a 
LISP interpreter in LISP, 
and discusses the storage 
functions of LISP. At this 
point the reader has been 
introduced to almost 
everything in the language, 
but is probably not certain 
how to write a program. 
The remainder of the book 
consists of programming 
examples. 

The first question which 
one should ask of a LISP 
book is how it treats 
language variations; LISP is 
not standardized. There are 
two major dialects (EVAL 



and EVALQUOTE), and 
many variations between 
implementations of the same 
dialect. The author discusses 
both of the major dialects, 
and points out where 
implementations are likely 
to differ. I have used two 
versions of LISP: a large 
version running on an 
Amdahl 470 and a Z80 ver- 
sion which was adapted 
from Dr Dobb's Journal of 
Computer Calisthenics and 
Orthodontia, number 30. 
Neither of these implementa- 
tions matched the language 
used in Let's Talk LISP, but 
neither of them required 
much work to make the 
sample programs run. In 
short, the book attempts to 
cover possible differences, 
and gets most of them, but 
unless you are using 
MACLISP at MIT, you will 
have to make some changes. 
If you want to learn LISP 
and you are not turned off 
by a lighthearted but 
thorough treatment of the 
subject, Let's Talk LISP is a 
good book to read. 




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Godel, Escher, Bach: An 
Eternal Golden Braid 

Douglas R Hofstadter 

Basic Books 

New York 1979 

742 pages plus notes and 

references, hardcover 

$18.95 

G'ddel, Escher, Bach is a 
book of youthful wisdom 
and deep beauty. It spans 
the domains of art, science 
and philosophy — a fact 
which evidently causes con- 
siderable consternation to 
book store clerks, who occa- 
sionally misshelve it with 
the "occult." 

At some fundamental 
level, the works of Bach, 
Escher and Godel may be 
seen as variant manifes- 
tations of a single common 
theme. Hofstadter uses this 
theme of recursion or self- 
reference to unify his explo- 
ration of questions _nd 
issues from such apparently 
disparate fields as artificial 
intelligence and molecular 
biology. 

Godel, Escher, Bach is an 
enchanting book, in the 
same sense that Lewis 
Carroll's writings are 
enchanting. Although 
Hofstadter, a contemporary 
American, writes more 
idiomatically and with less 
polish than Lewis Carroll, 
the book's childlike exu- 
berance, together with 
artistic forms, whimsical 
passages and concealed 
meanings, make it a sheer 
delight. The entire book has 
the form of a fugue — it is 
what it is about. Prose and 
dialogues alternate. The 
latter are in the spirit of 
Lewis Carroll and each imi- 
tates the form of a particular 
Bach composition. 

Hofstadter is a physicist 
by training and a computer 
scientist by vocation. 
Students of artificial in- 
telligence will appreciate his 
deeply knowledgeable treat- 
ment of this subject. Of 
particular interest are his 
remarks concerning 



188 February 1980 © BYTE Publications Inc 



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BYTE February 1980 



189 



representations of 
knowledge, and his specu- 
lations concerning the future 
of artificial intelligence. For 
example, 

"Question: Will a com- 
puter program ever 
write beautiful music? 
Speculation: Yes, but 
not soon. Music is a 
language of emotions, 
and until programs 
have emotions as com- 
plex as ours, there is no 
way a program will 
write anything beautiful 
. . . To think — and I 
have heard this sug- 
gested — that we might 
soon be able to com- 
mand a preprogrammed 
mass-produced mail- 
order twenty-dollar 
desk-model 'music box' 
to bring forth from its 
sterile circuitry pieces 
which Chopin or Bach 
might have written had 
they lived longer is a 
grotesque and shameful 
misestimation of the 
depth of the human 
spirit ..." 



Psychologists and other 
scientists who study humans 
are customarily reluctant to 
deal with such elusive topics 
as "consciousness" or "free 
will." Hofstadter has no 
such reticence, and conse- 
quently contributes unique 
and appealing insights to 
these subjects. In view of 
the book's global frame of 
reference, it is important to 
stress that the author is not 
reckless. On the contrary, 
one of his topics concerns 
the "nature of evidence," 
and in this regard it is clear 
that his own implicit criteria 
of acceptable evidence are 
definitely conservative. 
Neither is he a bigot, scien- 
tific or otherwise. His 
approach to centuries-old 
problems and dilemmas is 
characterized by carefulness 
and fair-mindedness. 

An interesting paradox 
arises from the observation 
that no two human brains 
are perfectly isomorphic; yet 
humans have a powerful 
ability to communicate with 
other humans, however 
remote in time or place. 



Hofstadter invents the con- 
cept of a "partial software 
isomorphism" between the 
brains of people who have 
similar thinking styles. An 
analysis of "Jabberwocky" 
translations clearly reveals 
the impossibility of exact 
translation between even 
closely related languages. 
One cannot help thinking 
that Hofstadter's book itself 
must represent the ultimate 
challenge for a translator. 
The dialogues not infre- 
quently contain more than 
two levels of meaning. 
There are puns and 
acrostics, word puzzles and 
number puzzles — indeed, 
levels of meaning sometimes 
communicate with one 
another. 

Although the prose is 
tractable, it is manifestly 
impossible to convey the 
true flavor of the book or to 
completely describe its sub- 
ject matter in a brief review. 
Perhaps the best synopsis is 
found in the book on page 
370, where the author 
diagrams a "tiny portion" of 
his "semantic network." This 



"tiny portion" contains more 
than 100 interrelated sym- 
bols including: Truth vs 
provability, Godel code, 
Genetic code, Recursion, 
Figure vs ground, Escher, 
Canons and fugues, RICER- 
CAR, Holism vs reduc- 
tionism, Minds, Computers, 
Turing and more. What 
Hofstadter has to say on 
these subjects is uniquely 
interesting because it is 
founded on knowledge, 
derived by honest (unpre- 
judiced) reasoning and 
expressed with a simple 
lucidity. 

In the past few decades, 
much has been said and 
written about "intelligence," 
a concept now suspect but 
once thought to have a clear 
intuitive meaning. Whatever 
human intelligence is, one 
feels that this book 
manifests its highest 
qualities. Godel, Escher, 
Bach is an exceptionally 
good book. II 

W Lloyd Milligan 
8604 Maywood Dr 
Columbia SC 29209 




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Circle 152 on inquiry card. BYTE February 1980 191 



A Financial 
Analysis Program 



John A Lehman 

716 Hutchins #2 

Ann Arbor MI 48103 



Introduction 

Financial analysis, as it will be used 
in this article, means the study and 
analysis of financial statements. 
Financial statements are the docu- 
ments which are produced by an ac- 
counting system; they report the posi- 
tion of a firm (such as the balance 
sheets shown in table 1) and how well 
it has done over the last period (in- 
come statements). They are used both 
by small businesses and by major cor- 
porations. The latter are. required to 
make public statements in annual 
reports and in filings with the 
Securities and Exchange Commission; 
these statements serve as one of the 
primary sources of information to 
investors. 

The program logic described in 
figure 1 is versatile enough to work 
on the financial statements of almost 
any company, although some state- 
ments may first need to be consoli- 
dated a bit. The basic tools used to 
analyze statements are ratios and 
percentages. These can be calculated 
for a firm, and then compared with 
both the firm's previous performance 
and with other firms in the same in- 



About the Author 

John A Lehman is a doctoral student in 
business administration at the University of 
Michigan. 



dustry. In this way, a comprehensive 
study can evaluate the position of the 
firm and identify trends in perfor- 
mance. 

There are a number of different 
people who can make use of this sort 
of analysis. Investors form a major 
group. Those who wish to make their 
own investment decisions rather than 
follow the suggestions of a broker or 
other advisor, usually want to base 
their investments on something more 
than blind faith. The analysis of 
financial statements is a good way to 
begin evaluating prospective invest- 
ments. Unfortunately, many inves- 
tors wish to evaluate a fairly large 
number of possibilities. This may pre- 
sent problems because the detailed 
analysis of ratios and percentages 
needed to evaluate your investments 
requires a great deal of time to 
calculate. This is where the personal 
computer comes in. With this pro- 
gram, you can evaluate a set of de- 
tailed reports in about the same time 
it takes to calculate a simple percen- 
tage analysis with a calculator. The 
results may be used as is, or used as 
inputs to any statistical calculations 
which you wish to use. In short, a 
personal computer can significantly 
reduce the time spent on the tedious 
calculations involved in financial 
analysis, and leave the analyst more 



time for creative thought. 

Investors are not the only ones who 
can use this sort of program. Banks 
regularly use ratio and percentage 
analysis to evaluate loan applications 
from businesses. Many banks are well 
equipped with computing facilities. 
But the businessman who is applying 
for the loan is often not. A banker is 
likely to be impressed if the financial 
statements submitted with the loan 
application include ratios and percen- 
tages. Not only does it make the 
banker's job easier, but it indicates 
that the applicant is well prepared. 

A pro forma statement is a useful 
indicator to provide. These are fore- 
casts of your financial position at 
some future point (eg: when the loan 
falls due). The program will also 
calculate pro formas. 

Aside from using all of these finan- 
cial indicators to impress the bank, a 
small businessman might want to use 
them to analyze his business. Where 
are things going well, and what 
weaknesses could stand some atten- 
tion? There is plenty of available 
documentation which shows how to 
interpret ratios and percentages, but 
again, the calculations are tedious. 

This program might also prove 
useful for the financial analyst — pro- 
fessional or academic. Since I count 
myself in the latter category, I have 



192 February 1980 © BYTE Publications Inc 



Table 1: The financial statements from the MITS corporation before it was absorbed. These figures come from the Annual Report. 
This illustrates the format used in a standard financial report. 



MITS INC 
Balance Sheet 

December 31 1975 and 1974 
Assets 



Current Assets: 
Cash 

Accounts receivable, less allowance 
for doubtful accounts of $5,500, 
$2,500 in 1974 (Note 2) 
Notes receivable, stockholder 
Inventories (Note 2) 
Current portion of prepaid expenses 
Total current assets 

Property, plant and equipment (at cost) 
(Notes 2 and 3): 
Tooling 

Transportation 
Shop equipment 
Office equipment 
Leasehold improvements 
Drafting equipment 

Less accumulated depreciation 

Other assets: 
Deposits 
Deferred portion of prepaid expenses 



1975 



$ 112,461 



1974 



$ 30,596 



258,790 

350 

640,432 

104,809 


35,808 

350 

266,219 

33,986 


1,116,842 


366,959 


225,821 

130,607 

55,150 

40,305 

12,749 

5,753 


117,669 

8,140 

13,349 

24,931 

9,848 

2,694 


470,385 
119,248 


176,631 
58,233 


351,137 


118,398 


1,766 
29,938 


240 


31,704 


240 


$ 1,499,683 


$ 485,597 



See accompanying accountants' report and notes to financial statements. 



Liabilities and Stockholders' Equity (Deficit) 



Current liabilities: 
Accounts payable ■ trade 
Customer deposits 
Working capital loans (Note 2) 
Current portion of long-term debt 

(Note 3) 
Accrued liabilities 

Total current liabilities 

Deferred portion of long-term debt 

(Note 3) 
Commitments (Note 4) 

Stockholders' equity: 

Common stock, $.01 par value, 25,000,000 
shares authorized, 947,495 shares 
issued in 1975, 902,940 shares issued 
in 1974 

Additional paid-in capital 

Retained deficit 

Less treasury stock, at cost, 1,100 shares 



1975 



1974 



$ 331,791 
455,425 
321,463 


$ 171,279 

85,517 

406,963 


39,288 
83,327 


8,602 
17,944 


1,231,294 


690,305 


118,626 


1,080 



9,475 

294,683 

(153,295) 

150,863 

1,100 


9,029 

250,575 

(465,392) 

(205,788) 


149,763 
$ 1,499,683 


(205,788) 
$ 485,597 



Table 1 continued on page 194 



February 1980 © BYTE Publicalions Inc 193 



Table 1 continued: 



MITS INC 

Statement of Income (Loss) 

Years ended December 31 1975 and 1974 



Sales 

Cost of sales 

Gross profit 

Expenses: 
Selling 

Administrative 
Other income and deductions 

Net income (loss) 

Net income (loss) per common 
share 



1975 




1974 


$ 3,240,772 


$ 


959,972 


2,112,551 




794,579 


1,128,221 




165,393 


441,596 
265,274 
109,254 




152,407 

176,295 

50,795 


816,124 




379,497 


$312,097 


$ (214,104) 


$ .33 


$ 


(.24) 



See accompanying accountants' report and notes to financial statements. 



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no doubt that the program is indeed 
useful for such people. I wrote this 
program to handle analytical pro- 
blems which I had to perform quite 
often. Again, the outputs from this, 
program may be used as they are, or 
as inputs to additional analyses. 

Overview of the Program 

The program in listing 1 is set up to ' 
work on standard financial state- 
ments with data for up to ten periods. 
It is arranged to use a standard chart 
of accounts for the income statement 
and balance sheet. Since the chart of 
accounts is not very specific, more 
detailed statements will have to be 
condensed first. This would be neces- 
sary for analysis in any case, since 
ratios are not usually calculated on 
the basis of all of the different 
categories of inventory, etc. The ten 
periods allowed may be either in 
years or quarters, and the output will 
be labeled correspondingly. Ten 
periods were selected since many 
annual reports and other published 
financial statements include ten-year 
summaries. 

For whichever periods are entered, 
the user may select either a ratio 
analysis, a percentage analysis, or 
both. The ratio analysis subroutine 
calculates fourteen different ratios. 



194 February 1980 & BYTE Publications Inc 



Circle 153 on inquiry card. 



f START J 



INITIALIZE 
CONSTANTS 



INPUT 

FINANCIAL 

STATEMENTS 



% ANALYSIS 



PERFORM 

PERCENTAGE 

CALCULATIONS 




RATIO 



PERFORM 

RATIO 

CALCULATIONS 




YES 




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PERCENTAGE 

CHANGE 



I INCOME 
■ — | STATEMENT 



ANALYSIS OF I- ■ 
PROFORMA 




INCREMENT 



MAKE AN 

INCREMENTAL 

CHANGE 



% ANALYSIS 



PERFORM 

PERCENTAGE 

CALCULATIONS 




YES 



RATIO 



PERFORM 

RATIO 

ANALYSIS 




% ANALYSIS 



PERFORM 

PERCENTAGE 

ANALYSIS 



J 




<4NOTHER\YES 
„ PROFORMA^ 

? 



f END ) 



Figure 1: Flowchart of the financial analysis program. 



February 1980 © BYTE Publicalions Inc 195 



Listing 1: BASIC listing of the financial analysis program. The entire program and the 
memory space required for BASIC can be stored in 16 K bytes of memory. A sample 
output of the program analyzing two years of data is also included. 



i o 

2 
2 1 
22 
23 
24 
25 
26 
£7 
28 
29 
30 
40 
50 
60 
70 
BO 
90 
1 00 
1 10 
1 20 
1 30 
I 40 
1 50 
1 60 

1 70 
180 
190 
200 

2 10 
220 
230 
240 
250 
260 
270 
280 
290 
300 

3 10 

3 20 
330 
340 
350 
360 
370 
380 
3<sr, 
400 

4 10 
420 
430 
440 
450 
460 
470 

4 8 
490 

5 00 
5 10 
5 20 
530 
5 40 
5 5 

5 60 
570 
580 
59 
f DC 

6 1 
6 20 
630 
640 
650 

6 60 
670 
630 
690 

7 00 



°EM FINANCIAL ANALY5I 5, RATIO i % 

D EM ALSO DOES P°OFORMAS USING 7, Of ABSOLUTE INCREMENTS 

REM Z(33, 11) IS THE MATRIX FOR THE F I N AN C I AL STATEMENTS 

REM PERIOD ELEVEN IS THE SPACE FOR THE PROFORMAS 

REM NS IS THE ACCOUNT NAMES VECTOR 

REM RJ IS THE RATIO NAMES, RC ) THE RATIO VALUES 

REM INDICATES QUARTERS OR YEARS, CS = COMPANY NAME 

REM EISA FIRST CELL POINTER, M IS A LAST CELL POINTER 

REM SWITCH CHANGES BETWEEN THE TELETYPE AND THE VIDEO DISPLAY 

Rjft, ,ip to TEN PERIODS CAN BE TESTED FOR. STATEMENTS 2 1-29 

REM SHOULD BE REMOVED IF YOU HAVE 16 K OR LESS OF MEMORY. 

REM BY JOHN A LEHMAN 

DIM Z( 33, 10>,NSC33),R(13, 1 3), RS( 13) 

FOR 1 = 1 TO 33: D EAD Nsri):NEXT I 

DATA "SALES", "OTH REV"* "TOT I N C", "C G S", "DE PR", " SGA" 

DATA "INT", "TAX", "DI V", "TOTAL EXP", "NET INC" 

DATA "CASH", "RCBLS", "INV, "PPL ITEMS", "TOT CUR" 

DATA "LAND", "BLDG/EQU", "ACC DEPR", "TOT FIXED", "OTH AS" 

DATA "TOT ASTS","ACCTS PBL", "NOTES PEL", "CUR LT" 

DATA "OTHE D L.1AB", "CUR LIAB","LT DEBT", "TOT LIAB" 

DATA "C STK", "APIC", "RE", "TOT CR" 

FOP 1=1 TO 13:READ Rf(I):NEXT 1 

DATA "CU D RENT", "ACID", "RCBL TO", "INV TO", "ASSET TO", "PROF ON SALES- 
DATA "ROA", "ROI ", "EPS", "PAYOUT", "EBT-EQU", "T INT EARN ED", "BK/ SHARE" 

INPUT "QUARTERS OR YEARS",'AS 

IF LEFTSf AS, 1 ) ="Q" THEN 210 

IF LEFTSC AS. 1) = "Y" THEN 250 

GOTO 160 

REM QUARTERS. LS IS A LABEL 

LS="QUARTEPS" 

LET 0=.2 5 

REM AN INCREMENT 

GOTO 2 70 

L$="YEARS " 

0=1 

"COMPANY NAME", 1 CI 



INPUT 
INPUT 
INPUT 
7 "OK. 



"FOR HOW'MANY PERIODS LO YOU HAVE F1GURES";N 

BEGINNING WITH JANUARY OF WHAT YEAR";Y 

FIGI'°ES FOR "JNJLj;" BEGINNING IN ";Y 
FOR J=l TO 3 3 
F0 D K=l TO N 
Y1 = 1NT( Y+ 0*K- 1 ) 
? NIC J),-" FOP "JY1 
INPUT Z(J,K) 
NEXT K 
NEXT J 

FOR J= 1 TO N 

? •■<« SHARES OUTSTANDING PERIOD "JJJ "?" 
INPUT Hi J) 
NEXT J 

INPUT"C0RRECT10NS",-AS:'IF LEFT$(AI, 1)="N" THEN 440 
INPUT "WHICH ACCT* g PD#"; J, K : 1 N PUT" VAL UE",' Z( J, K ) : GO TO 420 
B=1:REM 1ST CELL POINTER 
SW1 TCH 

'"DO YOU WANT t LIST OF COMPARATIVE FINANCIAL RATIOS'" 
- •■PLEASE ANSIER YES OR NO. THE ALTERNATIVE IS COMPARATIVE V 

|W rl J >i J 

IF LEF T <( A5, 1 ) ="Y" THEM 530 

IF LE FT$( A5, 1 ) ='•&)•' THEN 540 

? "PLtA c E AN C WE Q YE C 0° NO" 

GOTO 4 60 

COSUB 1030 

INPUT "DO YOU WANT COMPARATIVE •'. FROM INCOMES STMT 4 bS";AJ 

IF LE F TI( PI, 1 ) = "Y" THEN 590 

GOTO 9 40 

? "PLEASE AN SUE" YES OP NO" 

GOTO 5 40 

GO SUB 1310 

GOSl'B 1410 

INPUT "DO YOU WANT TO CREATE A PFOFORMA INCOME S TATEMEN T" i A3 



,. Y . 



THEN 650 
THEN 1340 



IF LEFTJf A J, I ) : 

1 F LEFTIC At, 1 ) = 

P0 T 610 

INPUT"D0 YOU WANT TO USE X CHANGES FROM LAST PERI Of; AS 

IF LEFTJC AI, 1 )="N" THEN 710 

IF LEFTSf AS, 1 ) ="Y" THEN 690 

GOTO 650 

GO SUB 1510 

GOTO 940 



Listing 1 continued on page 19 



These include the following: current, 
quick, acid test, accounts receivable 
in days, inventory turnover, asset 
turnover, profit on sales, return on 
assets, return on investment, earnings 
per share (simple), dividend payout, 
debt/equity, times interest earned, 
and book value per share. A detailed 
description of the use of these ratios 
and how they are calculated is in- 
cluded in the glossary at the end of 
this article. Percentages will be 
calculated for each period in two 
groups. Income statement items will 
be presented as percent of total sales; 
balance sheet items will be presented 
as percent of total assets. 

In addition to the above analyses, 
the program will calculate pro forma 
income statements and balance 
sheets. As I mentioned earlier, a pro 
forma statement is a prediction of 
what that statement will look like at a 
given time. The statements for the 
last period are the basis upon which 
the program calculates pro forma 
statements. These may be done by 
assuming a constant percentage 
change for all accounts, or by giving 
dollar amounts by which each 
account is predicted to change. As 
well as calculating the pro forma 
statements, the program will do ratio 
and/or percentage analyses on the 
pro formas if desired. This is partic- 
ularly useful when examining the 
effects of alternate possibilities. It is 
possible to come up with several 
alternatives for the coming period 
and observe the forecasted result for 
each one. 

Computer Program 

The financial analysis program has 
been written in BASIC and runs in 
16 K bytes or more, including the space 
required for BASIC, but not inclu- 
ding the space required for the system 
monitor. If you are running it with 
only 16 K (as I do) you will either 
have to remove some of the remark 
statements from the listing or adjust 
the dimension (DIM) statement to 
handle less than ten periods. 

The only peripheral-dependent 
part of the program is the SWITCH 
statement which occurs at lines 450 
and 1840. This is used to switch the 
logical console device between user 
defined and the Teletype. The config- 
uration upon which I run it allows 
me to set up all of the statements 



196 February 1980 © BYTE Publications Inc 



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BYTE February 1980 197 



Listing 1 continued: u - g vjc j eo display anc ) then have 

710 ? -ro you want to make INCREMENTAL changes fpom" , rpsiilts nrinted on the Teletvoe If 

720 input -the last pe°ict ufiNG amounts of change-;ai trie results primed on tne i eieiype . ir 

730 if left$<a$, i ) = "N ■• then 8eo your system does not allow for the 

740 if left^aj, n="Y- then 770 SWITCH command, you can leave it 

750 ■> "PLEASE ANSWER YES OR NO" . , .,, u 

7 60 goto 710 out with no ill effects. 

770 ? "eo v oi' want ji'st the income statement (enter is) or" If y OU have more than 16 K bytes 

780 input-income statemen t* bal an ce sheet (enter anything else)";z5 f memory, you may want to extend 

790 IF Z$="I S" THEN 840 

800 F=33 



the strings from lines 60 thru 120 and 



bio pem points to last account to BE usee 140 thru 150. This will make the out- 

8 20 go sub 1700 put more readable. 

830 GOTO 360 r S 

8 40 F= 1 1 

850 G0S"F 1700 

860 INPUT "DO YOU WANT A RATIO ANALYSIS OF THE PROFORMA (IF ANY)"! AS 

870 IF LEFTJfAS, I)="Y" THEN 890 j 

880 IF LEFTJfAS, 1 ) = "N " THEN 940 j 

390 LET N = 1 j 

900 if zs<>"is" then 930 Glossary 

910 ?"CAN'T CALC WITH JUST INC STATEMENT" 

920 goto 940 accounts receivable in days: Ac- 

930 gosub 1030 00 „ r „„_„, . counts receivable are divided by total 

940 INPUT "DO YOU WANT A 7. ANALYSIS OF THE PRO F RM A" J A$ •» 

950 if lef t s( a$> l > = "Y" then 930 sales to produce receivable turnover 

960 if lefts(ai, d="N" then iooo per year, then divided by 365. This 

970 GOTO 940 . . ». ,. t • r , 

980 fJ=M gives some indication of how fast 

990 go sub 1310 receivables are being collected. 

iooo input -co you vant another proforma-;as V alues vary with industry. Gener-' 

1010 IF LEFTKAJ, 1 )»"Y" THEN 650 n ,i i w i r j 

1020 if leftjcas, l ) = "n " then 1840 ally, the lower the number of days, I 

1030 pem subroutine to calculate patios the better. 

1 040 FOR i = b to n 

1050 i«i,i>»zci6,i>/Z(27,1)»hlm current ratio asset turnover: Net sales divided by ' 

loeo «fa,i>-czM2,i>+2H3,i)>/z<2?,niBEM acid test average total assets This is one indi-< 

1070 of 3, I )=365/fZ( 1,1 )/Z< 13, I) ) : REM RCBL LAYS uuciuge luiui Ubbeib. l nib lb one inui 

1080 9f 4, i > = 365/( z( n, i -,/?_(. i n, i ) ) : pem inv to cation of how well assets are being 1 . 

1090 Of 5, I )=Zf- 1' 1 >/Z(22, I) : «EM ASSET TO usec j 

1100 Of 6, iy-ZC 1 M )/?,< 1,1) ! OEM PROFIT ON SALES 

L 1 1 Q R( 7, I ) = .*( 1 1 , I > f < 22, I) : RE M ROA 

1120 R(S, I >='( 1 1, I)/( '( 33, I )-Z(29, I > > : =EM "01 ,..,.,, 

1130 p(9, i ) = tt 1 1, i >/h< i > : o£.m eps divided by the number of shares. 

M40 r( 10, i> = z(9, i >/zf i i, i > :°fm Ei'.' po How much the shares of stock are 

1150 R( 1 1, I )=Z( 29, I >/Z(22, I > : B EM D/E 

1160 H(l?,I)=( 7 .nl,l)t 7 <9,l)* 7 -'5.n*?.(7,I))/'.(7,I): 

1170 °f 1 3, I> = ( Z< 33, I >-Z< 29, 1 ) )/H( I ) : REM BK/SHARE i. u VI ± t- ■ • 

180 next i current ratio: A current account is 

1190 input"mo"e paper to top of page a press a KfcV'JAi cash or anything which can be con- 

laoo ? cj,"°atio analysis-:? verted into cash within one year. The ■ 

1210 ? "OATIOS FOR "JNJLI,,-" BEGINNING IN "JY:? . . . ,,,..,. 1 

1220 for 1 = 1 to 13 current ratio is obtained by dividing 

1230 ? Rsfi) the current assets by current liabi- 

! 250 y^nt^VJ- , , liiies ' V ihe ™tio is one, debts which 

12 60 ? Yi,R(i,J) must be paid within one year are just . 

1270 next j covered by assets which are expected] 

1230 NEXT I:?:?:? , . , . , . -r 

1290 return to " e received within one year. 10 

1300 rem subroutine to do i analysis maintain financial peace of mind the'' 

1310 input -move paper to top of page 4 press a KEY-jAj current ratio should be greater than' 

1320 ? "INCOME STATEMENT ITEMS AS % OF TOTAL INCOME" S 

1 330 FOP 1 = 1 T01 1 ° ne - 

1 3 40 ? N If I 3 ii,. -»• 1 »...».. 

1 350 for j=b to n debt/equity ratio: lotal liabilities 

i 360 Yi = iNTfY + o«j-D divided by total assets (also referred 

l 370 R(J, l) = Z( I, J)/Z( 3, J)* 100 
I 380 ? Yl, Pf J, l ) :NEXTJ 



book value per share: Common stock 
divided by the number of 
How much the shares of stc 
worth in an accounting sense. 



to as total equities). How much of the • 

139 nfxt iti firm's capital was furnished by 

1400 retupn creditors as opposed to owners. It- 

1410 ? "B.S. ITEMS AS •% OF TOTAL ASSETS":? , , , , , , , I 

1420 for 1 = 12 to 33 varies by industry, but the lower the 

1430 ? N$fi), better for safety, and the higher the 

1450 Y^iNTfMLj-n better for earnings per share. This, 

1460 Rf j, l ) = z( i, j >/zt 22, j) * i oo contradiction is due to something'. 

1470 ? yi, Rf J, i ) :next j called leverage, which is a fancy term 

1430 NFXT 1:?:?:? , . ° , I ' 

1490 return i or m vesttng other peoples money, 

isoo rem subroutine to calculate proforma with z changes and keeping the profits. 

1510 M=N+1:REM SAVE LAST CELL POINTER 

1520 b=m dividend payout: Cash dividends' 

1 530 FOR 1=1 T09 

1540 ? "CHANGE FOP ";NftI> 



divided by net income. This shows 
how much of earnings were paid to \ 
Listing l continued on page 200 investors as opposed to those kept for 



198 February 1980 © BYTE Publications lnc 



Circle 157 on inquiry card. 



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BYTE February 1980 199 



Listing 1 continued: 

1550 INPUT P 

1560 ZfI>M>=JfI»fM-l>)*( l + fP/100)) 

I 570 NEXT I 

1580 LET 7.(3,«) = 'JI,«)*Z(2.H) 

1590 ZC 10,M> = 

1 600 EC? 1 = 4 TO 3 

1610 LET Z(I0,1)=2(10,M)*Z(I,1« 

1620 ZC!l»M>»Z<3*M)-2< 10>M) 

1 630 NEXT I 

1640 INPUT"MO"E PAPER TO TOP OF PAGE AND PRESS A KEY";AS 

1 650 ? CS : ? 

1 660 F0 D 1=1 TO 11 

1 670 ? NSC 1 >, Z( IjM) 

1 68 NEXT I :? : ? :? 
169C »ETr°N 

1700 PEM CALCULATE P°OFORMA WITH IN CLEMEN TAL S 

1710 M = N + 1 

1 720 B = M 

1730 FOP 1=1 TO F 

1740 ?"AMOUNT OF CHANGE F0» "JNKI) 

1 750 INPUT P 

1760 LET Z(L.«)=ZXJL« fM- m+P 

1 770 NEXT I 

1780 INPUT"MOVE PAPE<? TO TOP OF PAGE 4 PRESS A KEY"; AS 

1 790 ? CI: ? 

1 300 FOR I = lTOf 

1810 ? N I ( I ) ., 7 . ci,~n 

1 820 NEXT I : ? : ? : ? 

18 30 PETL'PN 

1840 SVITCFt 

1850 ENT 



DO YO" M/yuT a LI c T OF C0"1 n 'A~ATI VE FINANCIAL RATIOS? 

PLEASE ANSVE^ YES 0^ WO. THE ALTERNATIVE IS COMPARATIVE 
-> vr. c 

~I9VE' PAPER TO TOP OF PAGE 4 PRESS A KEY? 



M 1TS RATIO ANALYSIS 

RATIOS FOP 2 YEARS BEGINNING IN 1974 



CURRENT 




1974 


.53159 


1975 


.907047 


ACID 




1974 


.0961952 


1975 


.301513 


RCBL TO 




1974 


13. 6 149 


1975 


29. 1469 


INV TD 




1974 


122. 29 1 


1975 


1 10.6'52 


ASSET TO 




1974 


1.97689 


1975 


2. 1609 7 


PROF ON SALES 




1974 


-. 223032 


1975 


.0963033 


ROA 




1974 


-. 4409 09 


1975 


.203 109 


ROI 




1974 


1 . 04041 


1975 


2.03394 


EPS 




1974 


-. 237236 


1975 


. 329392 


PAYOUT 




1974 





1975 





EBT-EOU 




1974 


1.42373 


1975 


.900137 


r INT EARNED 




1974 


-6. 1 368 


1975 


8.80243 


BK/ SHARE 




1974 


-. 228021 


1975 


. 158062 



Listing 1 continued on page 201 



use by the firm. This should be high 
for an income stock and low for a 
growth stock (all other things being 
equal). 

earnings per share: How much the 
firm made per share of common 
stock. Often this and the price/ 
earnings ratio are the only things 
investors look at. There are actually 
two ways of calculating the earnings 
per share ratio; the more complicated 
one would require a program much 
longer than that provided in this arti- 
cle. Both types of earnings per share 
ratios are required in annual reports, 
so it is best to rely on both for needed 
information if a firm has a compli- 
cated capital structure. 

inventory turnover: The cost of 
goods sold is divided by average in- 
ventory, and this is divided by 365. 

profit on sales: Net income divided 
by net sales. This provides a very 
conservative estimate of profits. 
Therefore, it is frequently used when 
companies wish to appear as though 
they are not making much of a 
profit. 

quick ratio (acid test): Unlike the cur- 
rent ratio, the quick ratio does not 
consider inventory and prepaid ex- 
penses as current assets. The quick 
ratio takes cash, marketable securi- 
ties; and accounts receivable, and 
divides these by current liabilities. 
The result is the proportion of liabi- 
lities falling due within one year, 
which can be covered by assets sure 
to be worth cash. It is normally a 
little less than one. 

return on assets: Net income divided 
by average total assets. How much 
you are making on what you have to 
make it with. As with any profit 
measure, the higher the better. 

return on investment: Net income 
divided by the quantity assets minus 
liabilities. This shows how much the 
firm made on what the owners put 
into it. Assets which were bought 
with borrowed money are not in- 
cluded in the base. 

times interest earned: The quantity of 
net income plus interest and tax 
payments divided by interest charges. 
This indicates how much more the 
firm made than was required to pay 
the interest on its debt. A firm which 
has a times interest earned ratio of 
less than one is bankrupt. 



200 February 1980 © BYTE Publications lnc 



Listing I continued: 
DO YOU WANT COMPARATIVE % FROM INCOMER STMT i BS? 
MOVE PACE" TO TOP OF PAGE 4 PRESS A KEY? 



YES 



INCOME STATEMENT ITEMS AS X OF TOTAL 
SALES 



K 
INCOME 



1974 


100 


1975 


100 


OTH REV 




1974 





1975 





TOT INC 




1974 


100 


1975 


100 


CGS 




1974 


52.7711 


1975 


65. 1867 


DEPP 




1974 


2.08339 


1975 


1.83227 


SGA 




1974 


34.2403 


1975 


21.8118 


I NT 




1974 


3. 12509 


1975 


1 . 23427 


TAX 




1974 





1975 





DIV 




1974 





1975 





TOTAL EXP 




1974 


39. 5321 


1975 


25. 183 


NET INC 




1974 


-22.3032 


1975 


9. 63033 



B.S. ITEMS AS * OF TOTAL ASSETS 



CASH 




1974 


6.3007 


1975 


7. 49898 


RCBLS 




1974 


7. 37402 


1975 


17.2563 


INV 




1974 


54.823 


1975 


42. 7045 


PPD ITEMS 




1974 


6.99943 


1975 


6.98874 


TOT CUR 




1974 


75.5686 


1975 


74.4719 


LAND 




1974 





1975 





BLDG/EOU 




1974 


36. 374 


1975 


31. 3656 


ACC IL" 




1974 


1 1 .992 


1975 


7.95155 


TOT FIXED 




1974 


24. 332 


1975 


23. 4141 


TH AS 




1974 


. 0494237 


1975 


2. 1 1405 


TOT ASTS 




1974 


100 


1975 


100 


ACCTS PEL 




1974 


35. 2718 


1975 


22. 1241 


NOTES PBL 




1974 


83.3067 


1975 


2 1 . 4354 


CUR LT 




1974 


1 . 77143 


1975 


2.619 7:. 


OTHEP LIAB 




1974 


21 . 3059 


1975 


35. 9244 



CUR LIAB 




1974 


142. 156 


1975 

LT DEBT 

1974 

1975 
TOT LIAB 

1974 

1975 
C STK 


82. 1036 

. 222407 
7.9 1 007 

142. 378 
90.0137 


1974 


1.85936 


1975 


. 6318 


A PIC 




1974 


51. 6014 


1975 


19. 6497 


RE 




1974 


-95.8391 


1975 


- 10.2218 


TOT CR 




1974 


100 


1975 


100 



DO YOU WANT TO CREATE A PROFORMA INCOME STATEMENT? YES 

DO YOU WANT TO USE * CHANGES FROM LAST PERIOD? YES 

CHANGE FOR SALES 

? 100 

CHANGE FOR OTH REV 

? 

CHANGE FOR TOT INC 

? 100 

CHANGE FOR CGS 

? 50 

CHANGE FOR DEPR 

? 50 

CHANGE FOR SGA 

7 50 

CHANGE FOR INT 

? 50 

CHANGE FOR TAX 

? 50 

CHANGE FOR DIV 

? 50 

MOVE PAPER TO TOP OF PAGE AND PRESS A KEY? 



MITS 



SALES 


6. 48 1 54E+06 


OTH =E<' 





TOT IMC. 


6. 48 1 54E+06 


CGS 


3. 1 6333E+06 


DEPR 


91500 


SGA 


1. 06031E+06 


INT 


60000 


TAX 





DIV 





TOTAL EXP 


4. 38063E+06 


NET INC 


2. 1 009 1E+06 



DO YOU WANT A 7. ANALYSIS OF THE PROFORMA? YES 
MOVE PAPER TO TOP OF PAGE * PRESS A KEY? 

K 
INCOME STATEMENT ITEMS AS 7, OF TOTAL INCOME 
SALES 



1976 


100 


OTH REV 




1976 





TOT INC 




1976 


100 


CGS 




1976 


48.89 


DEPR 




1976 


1.4117 


SGA 




1976 


16.3538 


INT 




1976 


.925705 


TAX 




1976 





DIV 




1976 





TOTAL EXP 




1976 


67. 5862 


NET INC 




1976 


32.4138 


DO YOU WANT 


ANOTHER PROFORMA? NO 



February 1980 « BYTE Publications Inc 201 



Another Plotter to 
Toy With, Revisited 

Design and Construction Details 



Robert K Newcomb 

502 Washington Ave 

Wilmette IL 60091 



Following the suggestion of Peter 
Lucas in the February 1979 issue of 
BYTE ("Another Plotter to Toy 
With," page 66) I built a plotter using 
an Etch-A-Sketch and two stepper 
motors. After solving the interface 
problem, I connected it to an I/O (in- 
put/output) port on my KIM-1 which 
is equipped with a teletypewriter, 8 K 
bytes of extra memory, and Tiny 
BASIC. Photo 1 shows the result: 
stepper motors mounted on the Etch- 
A-Sketch, along with a circuit board. 
The KIM-1 controls the apparatus 
using 4 bits of an I/O port. The step- 
per motors can be driven by any 
other computer having 4 bits of 
transistor-transistor logic (TTL) level 
output available. 

The Etch-A-Sketch proved to be 
able to draw bar graphs with 
excellent results, drawing an even, 
horizontal baseline, while accurately 
reproducing data from the computer's 
memory. I later tried geometric 
figures, including a parabola. Because 
each step is only 0.0085 inches (0.216 
mm), the device gives good approxi- 
mations of curves. The main limita- 
tion of my plotting system resides in 
the inability of Tiny BASIC to handle 
fractional numeric values. 

Stepping Motors and Drivers 

North American Philips series 
82701 stepping motors were chosen 
for drivers, even though the Etch-A- 
Sketch does not require all of the 
torque that these motors can pro- 
duce. The extra torque will come in 




Photo Is The stepper motor and control assembly is mounted on the Etch-A-Sketch . 
The knobs have been removed to allow attachment of the driven gears to the shafts. 



handy if you later wish to drive 
something else. The motors are 
driven by North American Philips (or 
Signetics) SAA 1027 driver integrated 
circuits which produce the succession 
of pulses needed to energize the four 
windings on each motor. Each driver 
receives toggling pulses to rotate the 
motor shaft, while a high or low-level 
signal on the rotation input deter- 
mines direction. A single 7406 buffer 
takes 5 V from the output ports and 
provides 12 V switching to both 



drivers. Figure 1 shows the circuit 
diagram. Each motor has an output 
torque of 7 ounce-inches at fifty steps 
per second and drives the Etch-A- 
Sketch through a 5 to 8 reduction 
gear. 

Electrical Construction 

A pre-etched and drilled Calectro 
J4-404 circuit board was used, after I 
sawed off the ends (to clear the step- 
per motors) and drilled holes for 
stand-offs. Two 14-pin integrated cir- 



202 February 1980 @ BYTE Publications Inc 



PAO LZ>- 



PA I O- 



>2.2K | ci 
7406 



^* 



+ I2V 
A 



100 
^vw— 



rh 



+ 5V 
A 



PA20 



P«3[> 



^ 



ICI + '2V 

7406 * 



Number Type 


+ 5 V 


GND 


IC1 7406 


11,13,14 


7 


IC2 SAA1027 




5,12 


IC3 SAA1027 




5,12 



J 



IC2 

SAAI027 



SET 
INPUT 



V l 
GND 



01 
Q2 
03 
04 



T 



IC 3 
SAA 1027 



SET 
INPUT 

GND 



GND 



01 

02 
03 
04 



T 



150ft 
I w 



+ I2V 
A 



~7h 



T I IN400I 
if if T TYPICAL 



i5on 



H2V 
A 



"* 



;rr 



■0>NUMBER 2 GRAY 

-C>NUMBER 2 YELLOW 

-CZ>NUMBER I GRAY 

-0>NUMBER I YELLOW 



+ I2V 
T_ 



A >NUMBERS I AND 2 
RED AND BLACK 



I 



IN400I 
YPICAL 
F 4 



-C7J> N IIMBER 2 GRAY 

-C7J>NUMBER 2 YELLOW 

-f~Z>NUMBER I GRAY 

-0>NUMBER I YELLOW 



+ I2V 

T_ 



-O NUMBERS I AND 2 
RED AND BLACK 



Figure 1: Schematic diagram of the stepper motor control and drive circuit. The integrated circuit IC2 controls the X axis; IC3 drives 
the motor for the Y axis. 



cuit sockets were mounted, one for 
the 7406 buffer and one to receive flat 
wire connections from the computer. 
For the 12 V power supply, run a 
two conductor, #18 cord directly to a 
fused (IV2 A) unregulated 12 V power 
supply (18 V maximum peak). 
Number 22 wire should be used for all 
other connections. The last step in 
wiring should be to connect the step- 
per motors. 

Mechanical Construction 

The motor frame is a 3 /i 6 inch 
(0.476 cm) thick aluminum plate, cut 
to 2V4 by 11 inch (6.35 by 27.94 cm) 
dimensions, with the stepping motors 
mounted on 8V4 inch (20.95 cm) 
centers to match the Etch-A-Sketch. 
You must drill clearance holes for the 
motor shafts (big enough to clear the 
twenty-tooth gears), and drill for the 
following items: four holes for circuit 
board stand-offs, two mounting holes 
per motor, and two holes at each end 
for the locating pieces that center the 
Etch-A-Sketch under the motor 



mount. Use of a drill press speeds up 
this work considerably. These 
locating pieces are % by 1 by 1% 
inches (0.95 by 2.54 by 4.76 cm) long 
and are tapped at the top for two 
screws each, and at bottom for two 
screws which hold a Vt by 1 by 11 
inch (0.635 by 2.54 by 27.94 cm) 
clamp piece that keeps the motor 
mount and Etch-A-Sketch together. 
Tack or staple two pieces of 3 /i 6 inch 
(0.476 cm) outside diameter rubber 
tubing to a piece of Vi by 1 by 4% 
inch (1.9 by 2.5 by 12.4 cm) wood 
to form a cushioned spacer between 
the motor mount and the Etch-A- 
Sketch. This prevents the plastic 
housing from cracking and spaces the 
assembly so that the gears line up. 
The driven gears (thirty-two teeth) 
are screw clamped to the Etch-A- 
Sketch control shafts after the knobs 
have been pulled off the device. 
When you slide the Etch-A-Sketch in- 
to place, move it until the gears mesh 
and bottom out against one another, 
and then slide it back about y 32 of 



an inch (0.08 cm). Lubricate the gears 
with a small amount of grease. 

Programming 

The first programming to be done 
is a routine which will rotate the step- 
ping motors in the desired direction, 
one at a time. To move the Etch-A- 
Sketch stylus in the +Y (up) direc- 
tion, output port pin PAl should be 
set equal to and pin PAO is then tog- 
gled. For — Y (movement down), set 
PAl to 1 and toggle PAO. Movement 
right and left (+X and —X) works 
the same way with pin PA3 setting 
direction. A machine language pro- 
gram which does this, written for the 
KIM-1, is given in listing 1. Figure 2 
gives the flowchart, and listing 2 
gives the code for a program to move 
the stylus along the Y axis according 
to data in memory, while the stylus 
moves one unit in the +X direction. 

If a series of memory locations con- 
tain a value of 0, the stylus will move 
only horizontally. If a memory loca- 
tion contains a 1, the stylus will move 



February 1980 © BYTF Publications Inc 203 




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can be a pointer in games, or a digiti- 
zer for charts and diagrams. It's a 
simple-to-use system for students, art- 
ists, engineers and graphic program- 
mers. 

The VersaWriter plugs directly 
into the Apple's game I/O and requires 
Disk II, Applesoft ROM and 32K of 
memory. 

We're offering the VersaWriter at 
an Introductory Price of only $179.95 
while current supply lasts. The Versa- 
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so take advantage of this opportunity 
by ordering your VersaWriter today. 

Ask for our free catalog of soft- 
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Dealer inquiries are welcome. 

©Rainbow Computing 1980 

' SPECIAL INTRODUCTORY OFFER 

□ Please send my VersaWriter to: 

Name 

Street 

City 



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Zip. 



□ Please send more information. 

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Signature 



Add $5.00 shipping and handling. Calif, 
residents add 6% sales tax. Delivery is 
2-4 weeks. 

RAINBOW COMPUTING, INC. 

9719 Reseda Blvd., Northridge, Ca 91324 
Telephone: (213)349-5560 

204 February 1980 © BYTE Publications Inc 



f START J 



OPEN PADD 
SET UP VEB 

ETC 



( END J 




ARE THE CUR- 
RENT AND END 
ADDRESSES 



THE SAME 



GET Y 

FROM MEMORY 



SET DD 
TO+Y 




CHANGE Y 
TO POSITIVE 



-*!•- 



( END J 




SET DD TO 

+ X AND TOGGLE 



TOGGLE Y 
IN DD 



LOAD PAD FROM 
DD AND DELAY 



LOAD PAD FROM 
DD AND DELAY 



INCREMENT 
VEB+1, + 2 



DECREMENT Y 



Figure 2: Flowchart of the routine in listing 2 which moves the stylus along the Y axis 
according to plot data in memory while maintaining constant movement along the X 
axis. 



up at a 45° angle. To load the plotting 
data from BASIC, we set up two 
jumps to machine language 
subroutines as shown in listing 3. The 
first subroutine sets up a memory 
pointer. The second subroutine in- 
crements this pointer to load con- 
secutive memory locations each time 



the BASIC program calls it. A Tiny 
BASIC parabola plotting program 
using these instructions is given as 
listing 4. 

When you set up your programs, it 
is nice to avoid running off the Etch- 
A-Sketch screen, although no harm 
will result. Thus you should try not 



Listing 1: Routines written in 6502 assembler for the KIM-1 to move the Etch-A-Sketch stylus along a single axis by individually 
activating the stepper motors. 





Hexadecima 


Address 


i Code 


3A40 


A9 0F 


3A42 


8D01 17 


3A45 


60 


3B1C 


A0 FF 


3B1E 


A2 20 


3B20 


CA 


3B21 


DOFD 


3B23 


88 


3B24 


D0F8 


3B26 


A5 DE 


3B28 


AA 


3B29 


A5 DF 


3B2B 


A8 


3B2C 


60 


3A46 


20 40 3A 


3A49 


A9 01 


3A4B 


8D00 17 


3A4E 


20 1C3B 


3A51 


A9 00 


3A53 


8D0O 17 


3A56 


20 1C3B 


3A59 


4C 49 3A 


3A66 


20 40 3A 


3A69 


A9 03 


3A6B 


8D00 17 


3A6E 


20 1C3B 


3A71 


A9 02 


3A73 


8D00 17 


3A76 


20 1C3B 


3A79 


4C 69 3A 


3A86 


20 40 3A 


3A89 


A9 04 


3A8B 


8D00 17 


3A8E 


20 1C3B 


3A91 


A9 00 


3A93 


8D00 17 


3A96 


20 1C3B 


3A99 


4C 89 3A 


3AA6 


20 40 3A 


3AA9 


A9 0C 


3AAB 


8D00 17 


3AAE 


20 1C3B 


3AB1 


A9 08 


3AB3 


8DO0 17 


3AB6 


20 1C3B 


3AB9 


4C A9 3A 



Label 



SPEED 



Op Code 




Mnemonic 


Operar 


LDAIM 


$000F 


STA 


PADD 


RTS 




LDYIM 


$00FF 


LDXIM 


$0020 


DEX 




BNE 


$3B20 


DEY 




BNE 


S3B1E 


LDAZ 


$00DE 


TAX 




LDAZ 


$00DF 


TAY 




RTS 




JSR 


$3A40 


LDAIM 


$0001 


STA 


PAD 


JSR 


SPEED 


LDAIM 


$00 


STA 


PAD 


JSR 


SPEED 


JMP 


$3A49 


JSR 


$3A40 


LDAIM 


$0003 


STA 


PAD 


JSR 


SPEED 


LDAIM 


$0002 


STA 


PAD 


JSR 


SPEED 


JMP 


$3A69 


JSR 


$3A40 


LDAIM 


$0004 


STA 


PAD 


JSR 


SPEED 


LDAIM 


$00 


STA 


PAD 


JSR 


SPEED 


JMP 


$3A89 


JSR 


$3A40 


LDAIM 


$000C 


STA 


PAD 


JSR 


SPEED 


LDAIM 


$0008 


STA 


PAD 


JSR 


SPEED 


JMP 


S3AA9 



Commentary 

SUBROUTINE TO OPEN PADD 

SUBROUTINE TO SET SPEED 

DECREMENT X, LOOP IF NOT 
DECREMENT Y, LOOP IF NOT 

RESTORE X AND Y 



MOVES STYLUS IN PLUS Y 
DIRECTION UNTIL INTERRUPTED 
SET Y ROTATION OFF, Y TRIGGER ON 
DELAY APPROPRIATELY 

SET Y TRIGGER OFF 



MOVES STYLUS IN MINUS Y DIRECTION 

UNTIL INTERRUPTED 

SET Y ROTATION ON, Y TRIGGER ON 



MOVES STYLUS IN PLUS X 
DIRECTION UNTIL INTERRUPTED 
SET X ROTATION OFF, X TRIGGER ON 



MOVES STYLUS IN MINUS X 
DIRECTION UNTIL INTERRUPTED 
SET X ROTATION ON, X TRIGGER ON 



Listing 2: Program written for the KIM-1 which moves the stylus along the X axis at a constant rate while movement along the Y axis 
is varied according to plot data stored in memory. 





Hexadecimal 




Op Code 








Address 


Code 


Label 


Mnemonic 


Operand 


Commentary 




3B11 


A5 DD 


LODPAD 


LDAZ 


$00DD 


THIS ADDS LOADING OF THE 




3B13 


8D00 17 




STA 


PAD 


OUTPUT PORT TO THE TIMING 




3B16 


8A 




TXA 




SUBROUTINE OF LISTING 1 




3B17 


85 DE 




STAZ 


$00DE 






3B19 


98 




TYA 








3B1A 


85 DF 




STAZ 


$00DF 






3B30 


A9 0F 




LDAIM 


$000F 


THIS IS THE PROGRAM SHOWN 




3B32 


8D01 17 




STA 


PADD 


IN FIGURE 2. ZERO PAGE 




3B35 


ADF5 17 




LDA 


SAL 


LOCATIONS CC THROUGH CF ARE 




3B38 


85 CC 




STAZ 


CURADL 


VECTOR EB. LOCATION DD 




3B3A 


ADF6 17 




LDA 


SAHI 


IS STORAGE FOR PORT A DATA 




3B3D 


85 CD 




STAZ 


CURADH 






3B3F 


A9 AD 




LDAIM 


$00AD 






3B41 


85 CB 




STAZ 


GETY 






3B43 


A9 A8 




LDAIM 


S00A8 






3B45 


85 CE 




STAZ 


$00CE 






3B47 


A9 60 




LDAIM 


$0060 






3B49 


85 CF 




STAZ 


$00CF 






3B4B 


A5CC 


COMEND 


LDAZ 


CURADL 


COMPARE VEB + 1 , VEB + 2 WITH 




3B4D 


CDF7 17 




CMP 


ENDALO 


END ADDRESS Listing 2 con. 


'imied on page 206 



February 1980 © BYTE Publications Inc 205 



Listing 


2 continued: 


3B50 


A5CD 


3B52 


EDF8 17 


3B55 


BO 43 


3B57 


20 CB 00 


3B5A 


10 OE 


3B5C 


A9 02 


3B5E 


05 DD 


3B60 


85 DD 


3B62 


98 


3B63 


49 FF 


3B65 


A8 


3B66 


C8 


3B67 


4C70 3B 


3B6A 


A9 FD 


3B6C 


25 DD 


3B6E 


85 DD 


3B70 


98 


3B71 


30 27 


3B73 


FOOD 


3B75 


A9 01 


3B77 


45 DD 


3B79 


85 DD 


3B7B 


20 11 3B 


3B7E 


88 


3B7F 


4C 70 3B 


3B82 


A9 07 


3B84 


25 DD 


3B86 


85 DD 


3B88 


A9 04 


3B8A 


45 DD 


3B8C 


85 DD 


3B8E 


20 11 3B 


3B91 


E6 CC 


3B93 


DO 02 


3B95 


E6CD 


3B97 


4C4B3B 


3B9A 


00 



YPLUS 



MITOPL 



SET PLS 



YMINUS 



TOGY 



TOGX 



END 



LDAZ 

SBC 

BCS 

JSR 

BPL 

LDAIM 

ORAZ 

STAZ 

TYA 

EORIM 

TAY 

INY 

JMP 

LDAIM 

ANDZ 

STAZ 

TYA 

BMI 

BEQ 

LDAIM 

EORZ 

STAZ 

JSR 

DEY 

JMP 

LDAIM 

ANDZ 

STAZ 

LDAIM 

EORZ 

STAZ 

JSR 

INCZ 

BNE 

INCZ 

JMP 

BRK 



CURADH 

ENDAHI 

END 

GETY 

SETPLS 

$0002 

SOODD 

$00 DD 

$00FF 



YMINUS 
$00FD 
$00DD 
$00DD 

END 

$3B82 

$0001 

$00DD 

$00DD 

LODPAD 

YMINUS 

$0007 

$00DD 

$00DD 

$0004 

$00DD 

$00 DD 

LODPAD 

CURADL 

S3B97 

CURADH 

COMEND 



TO END IF ADDRESSES MATCH 
Y POSITIVE 

SET ROTATION IN DD FOR - Y 
CHANGE -YTO +Y 



JUMP PAST SET PLUS ROTATION 
SET Y ROTATION FOR PLUS 



Y IS STILL MINUS, END ROUTINE 



Y =0, BRANCH 
TOGGLE Y IN DD 



LOAD PAD FROM DD AND DELAY 
DECREMENT Y 

JUMP BACK TO SECOND "IS Y MINUS' 
SET DD TO PLUS X 



TOGGLE X IN DD 



LOAD PAD FROM DD AND DELAY 
INCREMENT VEB+1 

INCREMENT VEB + 2 

REPEAT 

END 



Listing 3: Machine language subroutines which are called from the Tiny BASIC pro- 
gram of listing 4. The first routine sets up a memory pointer. The second routine incre- 
ments the pointer to load consecutive memory locations each time the BASIC program 

calls it. 





Hexadecimal 


Address 


Code 


1780 


A9 8D 


1782 


85 DA 


1784 


A9 00 


1786 


85 DB 


1788 


A9 02 


178A 


85 DC 


178C 


A9 60 


178E 


85 DD 


1790 


60 


1791 


20 DA00 


1794 


E6 DB 


1796 


DO 02 


1798 


E6 DC 


179A 


60 



Label 



Op Code 






Mnemonic 


Operand 


Commentary 


LDAIM 


$008 D 


SET UP MEMORY POINTER WITH 


STAZ 


$00DA 


MEMORY STARTING ADDRESS 


LDAIM 


$00 


SET LOW STARTING ADDRESS 


STAZ 


SUBPAD 




LDAIM 


$0002 


SET HIGH STARTING ADDRESS 


STAZ 


$00DC 


STARTING ADDRESS DEFAULT 


LDAIM 


$0060 


IS 0200. 


STAZ 


$00 DD 




RTS 




RETURN 


JSR 


$00DA 


LOAD MEMORY WITH CONTENTS 


INCZ 


SUBPAD 


OF ACCUMULATOR 


BNE 


$179A 




INCZ 


$00DC 


INCREMENT MEMORY POINTER 


RTS 




RETURN 



Listing 4: Program written for the KIM-1 in Tiny BASIC to plot a parabola using the 
machine language routines of listing 3. 

100 LET N = USR (6016) 

105 REM THIS IS 1780 HEXADECIMAL 

110 LETC = -120*120/10 

120 LET A = -119 

130 LETB = A*A/10 

140 LETD = B-C 

150 LETC=B 

160 IFD= -2 THEN LET D= -3 

190 IF D = 2 THEN LET D = 3 

200 LET D = D/3 

210 LET N = USR(6033,0,D) 

215 REM THIS EQUALS 1791 HEXADECIMAL 

216 REM SUBROUTINE IS ENTERED WITH D IN ACCUMULATOR 
220 LETA = A+1 

230 IF A> 120 GOTO 250 

240 GOTO 130 

250 END 



206 February 1980 S) BYTE Publications Inc 



Parts List 

2 gears: Sterling S1268ZS20AP1 (32 pitch, 32 teeth) or equivalent 

2 hubs: Sterling E62-4 (3/16 inch bore for above) or equivalent 

2 gears: Sterling S1086ZH2920P1 (32 pitch, 20 teeth, Vt inch bore) or equivalent 

2 stepper motors: North American Philips Controls Corp K82701P2 

2 stepper motor driver integrated circuits: Signetics SAA1027 

1 circuit board: Calectro J4-404 

Miscellaneous sheet aluminum and screws, wood block, and rubber tubing. 

A limited quantity of kits of the above items (ready to assemble with no cutting or drilling 
necessary) are available from the author for $109 postpaid, plus tax for Illinois residents. 

The following items are stocked by most electronic distributors: 

2 16-pin soldertail integrated circuit sockets 
2 14-pin soldertail integrated circuit sockets 

1 type 7406 integrated circuit hex inverting driver 
4 2.2K ohm V* W resistors 

4 12K ohm V* W resistors 

2 100 ohm Vi W resistors 
2 150 ohm 1 W resistors 
2 0.1 /jF 36 V capacitors 
8 1N4001 rectifier diodes 
1 0.001 nF 16 V capacitor 



to use more than 790 (decimal) 
memory locations in the program of 
listing 3. The total of all negative or 
positive numbers in the parabola 
plotting program of listing 4 should 
be less than decimal 558. 

The stepper drivers generate some 
electrical noise. I have no trouble 
with BASIC crashing, provided that 
the 12 V supply is off. For cassette 
recording, both 12 V and 5 V supplies 
should be off. For playback, both 
supplies can be on. Before disconnect- 
ing the I/O ports from the Etch-A- 
Sketch, push reset (RS) to switch the 
ports to their high impedance posi- 
tion. This eliminates the possibility of 
destroying the 7406 buffer device. 

Once you have loaded the program 
into memory and have stored it on a 
cassette, plug the connections from 
the 7406 buffer into your computer 
and turn on the 12 V supply (with the 
lVz A fuse in place). Using the 
monitor, execute the appropriate 
subroutines from listing 1 to move the 
stylus to the desired origin (typically 
upper left). Starting execution at hex- 
adecimal location 3B30 will plot 
whatever data is contained in 
memory. 

With experience in programming, 
you can set up a grid against which 
plotting can be done. The fine line 
produced by the Etch-A-Sketch 
makes measuring easy. Two advan- 
tages of the Etch-A-Sketch are that 
you don't use any memory preserving 
information on the screen, and the 
device is completely nonvolatile. 



Begin a plot today, shut down your 
system before finishing, and weeks 
later you can come back and continue 
the plot. You will also experience the 



satisfaction of watching your com- 
puter move things in the real world, 
rather than manipulate shadows on a 
television screen. ■ 



NOW, FROM MOUNTAIN HARDWARE. 

THE 100,000 DAY CLO< 



Put your S-100 Computer 
on the clock. 

A real time clock could double the 
utility of your computer. Time events 
in 100,l(,S increments for up to 100,000 
days (over 273 years). Program events 
for the same period with real time 
interrupts that permit pre- 
programmed activities to take 
place... without derailing on-going 
programs. Maintain a log of computer 
usage. Call up lists or appointments. 
Time and date printouts. Time events. An 
on-board battery keeps the clock running in 
the event of power outage. 

Mountain Hardware also offers a complete line 
of peripheral products for many fine computers 

J|J( Available at your dealer's. Now. 

Mountain Hardware, Inc. 




m 




300 Harvey West Blvd. 
Santa Cruz, CA 95060 (408) 429-8600 



Circle 160 on inquiry card. 



February 1980 IS BYTE Publications Inc 207 



Circle 161 on inquiry card. 



DEFINITELY 
DIFFERENT . 




FROM HAYDEN 

New! Z-80 AND 8080 ASSEMBLY 
LANGUAGE PROGRAMMING 

(Spracklen) An extensive introductory 
look at assembly language 
programming for the 8080 and Z-80 
processors. Programming techniques 
are presented along with the 
instructions. Numerous diagrams and 
examples are provided, plus exercises 
with answers. #5167-0, $7.95 

New! DESIGNING MICROCOMPUTER 
SYSTEMS (Pooch & Chattergy) 
Provides both hobbyists and electronics 
engineers with the information 
necessary to build microcomputer 
systems. Also discusses the hardware 
aspects of microcomputer systems, 
including microprocessor architecture, 
input and output ports, interrupt 
systems, programmable clocks, 
memory units, etc. #5679-6, $8.95 

New! SIXTY CHALLENGING 
PROBLEMS WITH BASIC 
SOLUTONS (Spencer) Will sharpen 
your programming skills through 
games, puzzles, science problems, 
business problems and mathematical 
recreations. #5180-8, $6.95 

New! PASCAL WrTH STYLE: 
Programming Proverbs (Ledgard & 
Nagin) A style guide for writing more 
accurate, error-free programs. Includes 
samples of PASCAL programs and a 
special chapter showing how to use the 
top-down approach. #5124-7, $6.95 



Available at your 
local computer store. 

Hayden Book Company, Inc. 

50 Essex Street, Rochelle Park, NJ 07662 

208 February 1980 © BYTE Publications Inc 



BYTE's Bits 



Personal Computers for 
the Handicapped 

The Applied Physics 
Laboratory of Johns 
Hopkins University is the 
location of a project being 
organized by Paul L Hazan. 
This project is a program for 
the application of personal 
computers to the problems 
of people with various 
physical handicaps. 

Various applications 
include simple computer- 
controlled communications 
aids for quadriplegics, inter- 
faces between computers 
that allow hearing-impaired 
individuals to communicate 
via telephone, and other 
very inexpensive applica- 
tions of off-the-shelf hard- 
ware. A design contest with 
substantial prizes is being 
considered. 

Those interested in more 
details may contact Paul L 
Hazan, Assistant to the 
Director for Advanced 
Computer Technology, 
Johns Hopkins University, 
Applied Physics Laboratory, 
Johns Hopkins Rd, Laurel 
MD 20810. ■ 



BYTE's Bugs 



Chess Moves Rechecked 

Thanks to John Gropper 
for pointing out an error in 
"Alpha-Beta Pruning," by 
W D Maurer (November 
1979 BYTE, page 84). Figure 
1 gives white's second move 
as Q-N7. The correct move 
is Q-N8. The move is shown 
correctly in figure 2.B 



CROMEMCO 

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RAM memory • RS232 special interface • print- 
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THE HDD - 11/22 megabyte hard disk 
system, for use with existing systems. DMA 
controller, transfer rate of 5.6 megabytes/sec. 
HDD-11, List $6995. . OUR PRICE ONLY $5939 
HDD-22, List $11,995 $10,189 



L_ L. 



CROMEMCO SYSTEM 3 

Features 4 MHz CPU, 64K of RAM, dual-sided 
PerSci 299B floppy disk drive (provision for in- 
stalling a second 299B), RS232C interface, print- 
er interface. All Cromemco systems are assem- 
bled and tested, ready to use. 
With 64K of RAM, List $6585 .... ONLY $5485 
— NOW DOUBLE THE CAPACITY! — 

CROMEMCO SYSTEM 2 - 

With 64K of RAM, two minifloppy disk drives, 
RS232 interface and printer interface board. 
System 2 w/64K RAM, List $3990 $3390 

Z-2 COMPUTER SYSTEM - can 

be rack mounted. Z-80 processor, 21 slots, 
power supply, front cover panel. Includes fan 
and all edge connectors. Assembled and tested. 
CRO-10000-A (Z-2W), List $995 $845 

Z-2D DISK COMPUTER similar 

to Z-2 but comes with floppy disk controller, 
DOS, and minifloppy disk drive. A complete 
system with the addition of a RAM board. 
CRO-10020-A (D2D-W), List $1990 $1689 

CROMEMCO BOARDS 

CRO-31010-A (SCC-W) 4 MHz Single Card 
Computer, Assem. /tested, List $450 .... $382 
CRO-310001-K (ZPU-K) 4 MHz CPU card. Kit 250 
CRO-31000-A (ZPU-W) Above, assembled . 335 
CRO-32020-A (16KZ-W) 16K RAM card with 
bank select, assem. /tested, List $595 .... 495 

SHIPPING, HANDLING 6 INSURANCE: Add $2 lor boards 
Assembled systems shipped freight collect. All prices subiect 
to change and all offers subject to withdrawal without notice. 
Above prices are for prepaid orders Slightly higher prices pre- 
vail for other-than-prepaid orders 

WRITE FOR FREE CATALOG P 

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Circle 162 on inquiry card. 




A 




i T i 



I 



LIBRARY. . . 



with a complete a 

PAPERBYTE and 



YOU JUST BOUGHT A PERSONAL 
WHAT is filled with practical ideas 
for using a personal computer at 
home or work. It will take you 
through the steps necessary to write 
your own computer programs, and 
then show you how to use structured 
design techniques to tackle a variety 
of larger projects. The book contains 
over 60 ready-to-use programs writ- 
ten in Radio Shack TRS-80 Level II 
BASIC in the areas of educational 
games, financial record keeping, 
business transactions, disk-based data 
file and word processing. 

ISBN 0-07-018492-5 

Authors: Thomas Dwyer and 
Margot Critchfield 

Pages: 256 Price: $11.95 

BEGINNER'S GUIDE FOR THE 
UCSD PASCAL SYSTEM is written 
by the originator of the UCSD Pascal 
System. This highly informative book 
is designed as an orientation guide for 
learning to use the UCSD Pascal 
System. Once familiar with the 
system, you will find the guide an in- 
valuable reference tool for creating 
advanced applications. This book 
features tutorial examples of pro- 
gramming tasks in the form of self- 
study quiz programs. 

ISBN 0-07-006745-7 

Author: Kenneth Bowles 

Pages: 184 Price: $11.95 



PAPERBYTE BOOKS 
are BYTE BOOKS with 
bar codes included! 

SUPERWUMPUS is an exciting com- 
puter game incorporating the original 
structure of the WUMPUS game 
along with added features to make it 
even more fascinating. Programmed 
in both 6800 assembly language and 
BASIC, SUPERWUMPUS is not only 
addictively fun, but also provides a 
splendid tutorial on setting up 
unusual data structures. This is a 
PAPERBYTE® book. 

ISBN 0-07-019342-8 

Author: Jack Emmerichs 

Pages: 56 Price: $6.00 

TINY ASSEMBLER 6800: Version 3.1 
has an updated version of the user's 
guide, the source, object and PAPER- 



BYTE® bar code formats of both 
Version 3.0 and 3.1. This book is the 
most complete documentation possi- 
ble for Jack Emmerichs' Tiny 
Assembler. 

ISBN 0-07-019341-X 

Author: Jack Emmerichs 

Pages: 80 Price: $9.00 

RA6800ML: AN M6800 
RELOCATABLE MACRO 
ASSEMBLER provides the necessary 
background for coding programs in 
the 6800 assembly language, and for 
understanding the innermost opera- 
tions of the Assembler. The PAPER- 
BYTE® bar code representation of 
the Assembler's relocatable object file 
is included. 

ISBN 0-07-028056-8 
Author: Jack E. Hemenway 
Pages: 184 Price: $25.00 

LINK68: AN M6800 LINKING 
LOADER provides everything 
necessary for the user to easily learn 
about the system. In addition to the 
source code and PAPERBYTE® bar 
code listings, there is a detailed 
description of the major routines of 
the Linking Loader, including 
flowcharts. 
ISBN 0-07-024120-1 
Authors: Robert D. Grappel 

& Jack E. Hemenway 
Pages: 72 Price: $8.00 

BASEX, a new compact, compiled 
language for microcomputers, has 
many of the best features of BASIC 
and the 8080 assembly language — 
and it can be run on any of the 8080 
style microprocessors: 8080, Z-80, or 
8085. Subroutines in the BASEX 
operating system typically execute 
programs up to five times faster than 
equivalent programs in a BASIC in- 
terpreter — while requiring only 
about half the memory space. The 
author, Paul Warme, has also includ- 
ed a BASEX loader program which is 
capable of relocating programs 
anywhere in memory. This is a 
PAPERBYTE® book. 

ISBN 0-07-068290-9 

Author: Paul Warme 

Pages: 88 Price: $8.00 

TRACER: A 6800 DEBUGGING 
PROGRAM includes a reprint of 
"Jack and the Machine Debug" (from 
the December 1977 issue of BYTE 



magazine), TRACER program notes, 
complete assembly and source listing 
in 6800 assembly language, object 
program listing, and machine 
readable PAPERBYTE® bar codes of 
the object code. 
ISBN 0-07-024121-X 
Authors: Robert D. Grappel 

& Jack E. Hemenway 
Pages: 24 Price: $6.00 



MONDEB: AN ADVANCED M6800 
MONITOR-DEBUGGER features ease 
of use and minimum memory re- 
quirements while retaining maximum 
versatility. The result is an extremely 
versatile program. The size of the en- 
tire MONDEB is less then 3K. This is 
a PAPERBYTE® book. 

ISBN 0-07-049556-4 

Author: Don Peters 

Pages: 88 Price: $5.00 



BAR CODE LOADER contains the 
general bar code loader algorithm 
description in flowchart form plus 
detailed assemblies of program code 
for 6800, 6502, and 8080 processors. 
Individuals with computers based on 
these processors can use the software 
directly. Individuals with other pro- 
cessors can use the provided func- 
tional specifications and detail ex- 
amples to create equivalent programs. 
This is a PAPERBYTE® book. 

ISBN 0-07-008856-X 

Author: Ken Budnick 

Pages: 32 

Price: $2.00 

K2FDOS: A FLOPPY DISK 
OPERATING SYSTEM FOR THE 
8080. K2FDOS is a complete software 
package and includes all the informa- 
tion and specific routines necessary to 
bootstrap and run a powerful floppy 
disk operating system on an 
8080-based microcomputer. This 
small (4K), but powerful, system in- 
cludes many of the file handling 
features of large operating systems. It 
comes complete with source code 
listings in the hexadecimal format, 
and machine readable (PAPER- 
BYTE® ) bar code format listings for 
individual K2FDOS programs. 

ISBN 0-07-069206-8 

Author: Kenneth B. Welles 

Pages: 192 

Price: $20.00 



ssortment of 

BYTE BOOKS ! 



The following BYTE 
BOOKS are collections 
of favorite articles from 
past issues of BYTE 
magazine, plus new 
material. 



THE BYTE BOOK OF COMPUTER 

MUSIC combines the best computer 
music articles from past issues of 
BYTE magazine with exciting new 
material — all written for the com- 
puter experimenter interested in this 
fascinating field. 

An ardent do-it-yourselfer or arm- 
chair musicologist will find this book 
to be a useful addition to the library. 

ISBN 0-07-043097-7 

Editor: Christopher P. Morgan 

Pages: 144 Price: $10.00 

CIARCIA'S CIRCUIT CELLAR offers 
a detailed look at the marvelous pro- 
jects which let you do useful things 
with your microcomputer. Each arti- 
cle is a complete tutorial. Using 
amusing anecdotes to introduce the 
articles and an easy-going style, Steve 
presents each project so that even a 
neophyte need not be afraid to try it. 

ISBN 0-07-010960-5 

Author: Steve Garcia 

Pages: 128 Price: $8.00 



THE BYTE BOOK OF PASCAL is a 

general introduction to Pascal and 
contains numerous articles, language 
forums and letters from past issues of 
BYTE magazine. In addition, this 
book contains several important 
pieces of software including two ver- 
sions of a Pascal compiler - one writ- 
ten in BASIC and the other in 8080 
assembly language; a p-code inter- 
preter written in both Pascal and 
8080 assembly languages; a chess 
playing program; and an APL inter- 
preter written in Pascal. 

ISBN 0-07-037823-1 

Editor: Blaise W. Liffick 

Pages: 342 Hardcover Price: $25 

PROGRAMMING TECHNIQUES is 

a series of collected articles concerned 
with the art and science of computer 
programming. The first volume in the 
Programming Techniques series is en- 
titled PROGRAM DESIGN. The pur- 
pose of the book is to provide the 
personal computer user with the 
techniques needed to design efficient, 
effective, maintainable programs. 

ISBN 0-07-037825-8 

Editor: Blaise W. Liffick 

Pages: 96 Price: $6.00 

SIMULATION is the second volume 
in the Programming Techniques 
series. Both theoretical and practical 
applications are included. Particularly 
stressed is simulation of motion, in- 



cluding wave motion and flying ob- 
jects, and the use of simulation for 
experimentation. 

ISBN 0-07-037826-6 

Editor: Blaise W. Liffick 

Pages: 126 Price: $6.00 

NUMBERS IN THEORY AND 

PRACTICE is the third book in the 
series. It includes information of 
value to both the novice and the ex- 
perienced personal computer user. 
The mechanics of the binary system 
are discussed, including software divi- 
sion and multiplication, as well as 
floating point numbers, numerical 
methods, random numbers, and the 
mathematics of computer graphics. 

ISBN 0-07-037827-4 

Editor: Blaise W. Liffick 

Pages: 192 Price: $8.95 

BITS & PIECES is the fourth volume 
in the Programming Techniques 
series. It covers various topics of in- 
terest to programmers. It is a collec- 
tion of the best articles from past 
issues of BYTE magazine plus new 
material collected specifically for the 
series, on subjects such as 
multiprogramming, stacks, interrupts, 
optimization, and real-time process- 
ing. 

ISBN 0-07-037828-2 

Editor: Blaise W. Liffick 

Pages: 160 Price: $8.95 

(available Spring '80) 



m 



Circle 163 on inquiry card. 



Pl- 



ease send 



Name 



Title 



Company 



Street 



City 



State/Province 



Code 



□ Check enclosed in the amount of $ 

□ Bill Visa □ Bill Master Charge 
Card No. Exp. Date. 



Add 60<t per book to cover postage and handling. 



BITE 

.BBLIMS. 



70 Main Street, 

Peterborough, New Hampshire 03458 



. copies of Superwumpus 

. copies of Tiny Assembler 6800 

. copies of RA6800ML: An M6800 Relocatable 

Macro Assembler 
. copies of LINK68: An M6800 Linking Loader 
. copies of BASEX 

. copies of TRACER: A 6800 Debugging Program 
. copies of MONDEB: An Advanced M6800 

Monitor-Debugger 
. copies of You Just Bought a Personal What? 
. copies of Beginner's Guide for the UCSD 

Pascal System 
. copies of Bar Code Loader 
. copies of K2FDOS: A Floppy Disk Operating 

System for the 8080 
. copies of The BYTE Book of Computer Music 
. copies of Ciarcia's Circuit Cellar 
. copies of The BYTE Book of Pascal 
. copies of Program Design 
. copies of Simulation 

. copies of Numbers in Theory and Practice 
. copies of Bits & Pieces 



WhsftNew? 



PERIPHERALS 



90 M Byte Disk Subsystem 




The model AM 410 90 M byte (for- 
matted) disk subsystem is based on the 
CDC Phoenix drive. The unit consists of 
75 bytes of fixed disk capacity combined 
with 15 M bytes of removable cartridge. 
The controller is interrupt driven and 
operates on full 512-byte sector data 
transfers. The AM 410 has an average 
access time of 30 milliseconds and pro- 
vides full cyclic redundancy check 
(CRC) and sentinel bit error checking 
capabilities. Up to four drives can be 
connected to one controller for a total 
storage capacity of 360 M bytes of data. 
The AM 410 is designed to work with 
Alpha Micro's AMOS operating system 
and other operating systems on either 
the 8- or the 16-bit S-100 bus. The self- 
contained unit is available from Alpha 
Micro, 17881 Sky Park N,. Irvine CA 
92714, for under $15,000. 

Circle 451 on inquiry card. 



Printers and Plotters for 
the Apple II, PET, TRS-80 

Axiom Corp, 5932 San Fernando Rd, 
Glendale CA 91202, has introduced the 
EX-801 and EX-820 series printers and 
plotters for the Apple II, PET, and 
TRS-80. Each printer can be plugged 
into the different microcomputers 
without any special user adaptation. 

The EX-801 features the full 96-char- 
acter ASCII set, 80 characters per line, 
80 columns, and full user control of in- 
dividual dots in graphics mode. 

The EX-820 includes all the features of 
the EX-801 plus the capability of being a 
full plotter that can generate schematics, 
musical scores, charts and other 
displays. The EX-820 can print any 
graphics image with up to 128 dots per 
inch resolution. 

The price for the EX-801 is $535. 
Circle 452 on inquiry card. 



The Sorcerer's Voice 

The model SV-100 is a self-contained 
device that generates tones, musical 
notes, and sound effects. The unit plugs 
into the parallel output port of the 
Sorcerer and features a built-in speaker. 
The SV-100 utilizes twenty-one tones in- 
cluding twelve musical notes. A cassette 
includes an INTRO for the SV-100; 
SDEFT, a sound effects program; 
MUSIC, a real-time music composition 
program; and HORSE, a horse race 
game with sound effects. 

The SV-100 is available from Indiana 
Digital Corp, POB 3755, South Bend 
IN 46619, for $49.95. 

Circle 453 on inquiry card. 



100% Error Free Floppy 
Disks 




DVSAN 

MINI DISKETTES 



Error free single- and double-sided 
5-inch floppy disks in 35- or 40-track 
versions are available from Dysan Corp, 
5440 Patrick Henry Dr, Santa Clara CA 
95050. They are available in hard- or 
soft-sectored versions. 

Circle 454 on inquiry card. 



Standard Letter-Quality, 
Wide Carriage Printer 

The CPT Rotary V is an up to 40 
character per second (cps) serial printer 
with letter-quality printout, a metal 
daisy print wheel, and the printer can be 
used with the CPT 6000 and 8000 word 
processing systems. Featured are an 
adjustable platen for multiple part 
forms, ribbon lift for position accuracy, 
and bidirectional paper feed for forms 
fill-in applications. The Rotary V is 
priced at $4000 and is available from 
CPT Corp, 1001 2nd St S, Hopkins MN 
55343. 

Circle 455 on inquiry card. 



Universal Graphics Display 
Peripheral 




The G-Box is a peripheral device 
which can be used with any computer to 
add high-density graphics. The video 
image output is a matrix of 512 by 240 
dots with an expansion capability. Con- 
nection to the computer is through an 
RS-232 serial link. The G-Box accepts 
standard ASCII codes and it does not 
require assembly language routines. It 
can be controlled from BASIC and other 
languages. Interfaces for joysticks, serial 
and parallel ports, a light pen interface, 
and other options are built into the unit. 
The G-Box can be adapted to work on 
the TRS-80, Heath, Commodore, North 
Star, and other microcomputers. Prices 
range from approximately $350 for the 
primary version (without cabinet), up to 
over $2000 for terminal units with full 
options. Contact Objective Design Inc, 
POB 20325, Tallahassee FL 32304. 
Circle 456 on inquiry card. 



Where Do New Products Items 
Come From? 

The information printed in the new 
products pages of BYTE is obtained from 
"new product" or "press release" copy 
sent by the promoters of new products. If 
in our judgment the information miglit 
be of interest to the personal computing 
experimenters and homebrewers who 
read BYTE, we print it in some form. We 
openly solicit releases and photos from 
manufacturers and suppliers to this 
marketplace. The information is printed 
more or less as a first in first out queue, 
subject to occasional priority modifica- 
tions. While we would not knowingly 
print untrue or inaccurate data, or data 
from unreliable companies, our capacity 
to evaluate the products and companies 
appearing in the "What's New?" feature is 
necessarily limited. We therefore cannot 
be responsible for product quality or com- 
pany performance. 



212 February 1980 © BYTE Publications Inc 



SOFTWARE and PERIPHERALS 



IBM to CP/M or CP/M to 
IBM Transfer Utility 
Program 

The IBM2CPM program uses an IBM 
or equivalent mainframe to develop 
systems for microcomputers using cross- 
compilers and assemblers. The resulting 
source programs are transferred to the 
microcomputer via a standard 8-inch 
floppy disk. This system enables a 
microcomputer to act as a data entry 
system for a large mainframe. The pro- 
gram features interactive operation that 
allows users to specify which files to 
copy, the ability to display the directory 
on an IBM standard interchange floppy 
disk, and more. IBM2CPM is available 
from Precision Computer Systems Inc, 
1737 N First St, San Jose CA 95112 for 
$95. 

Circle 457 on inquiry card. 



Bus(iness) 1 

Designed for SwTPC 6800 and PET 
systems, this package contains thirty 
programs, including payroll, cash flow, 
profit and loss accounting, stock con- 
trol, invoices, sales ledger, updating 
address files, and more. The package 
can run up to four companies, eight 
bank accounts, fifty agents, 999 
customers or suppliers, 1000 stock items 
and two-hundred employees, depending 
on disk storage. The program can run in 
20 K bytes of memory and has been 
adapted to the 6502 processor. It costs 
$275 plus value added tax (VAT). For 
more information, contact G W Com- 
puters Ltd, 89 Bedford Court Mansions, 
Bedford Ave, London WCl ENGLAND. 
Circle 458 on inquiry card. 



Software Protection for 
S-100 Bus Systems 

International Product Development 
Inc, 1708 Stierlin Rd, Mountain View 
CA 94043, has developed the LW100 
board that operates with standard soft- 
ware, as well as protected software that 
can be copied for a user's computer. 
Each LW100 board contains a key that 
is different from all other boards. The 
protected software has a key lock pro- 
grammed to work with only one com- 
puter. Manufacturers and software 
houses that wish to protect their soft- 
ware would supply the customer with a 
LWI00 board and protected software. 
Future sales to that cutomer require only 
the protected software that works with 
the customer's keyed computer. The cost 
for the board is 5139. 

Circle 459 on inquiry card. 



WIZRD Multitasking Disk 
Operating System 

Wintek's system includes true device- 
independent (virtual) input/output 
(I/O); HEAP memory management for 
efficient memory allocation for I/O buf- 
fers; and command indirection, which 
allows commands to be read from files 
with no operator intervention. It is 
helpful for systems used by untrained 
operators. WIZRD is included with 
Wintek's 48 K, dual-drive SPRINT 68 
microcomputer for $3995, or alone for 
$495. For information, contact Wintek 
Corp, 1801 South St, Lafayette 
IN 47904. 

Circle 460 on inquiry card. 



Word Processor for 
Apple II and Apple II 
Plus Systems 

Super-Text is a multiple paging system 
that allows users to view two texl 
screens simultaneously, keep notes or 
instructions on one text screen and edit 
on the other. It features full floating cur- 
sor and cursor control; insertion and 
deletion of characters, words or lines; 
tabbing; justification; full scrolling; 
movement to the last change made in 
the text; global search and replace; 
block operations; and advanced file 
handling and print controls. The system 
runs in 48 K bytes of memory and costs 
$99.95. It is available from Muse Co, 
7112 Darlington Dr, Baltimore MD 
21234. 

Circle 461 on inquiry card. 



Text Formatter for UCSD 
Pascal Systems 

Using the Moonshadow Text Format- 
ter, documents produced with the screen 
editor are post-processed to provide 
underlining, automatic pagination, and 
other essential text-processing functions. 
It takes standard Pascal text files, 
operates on them, and sends fully for- 
matted text output to the console 
display, a printer, or a disk file. Moon- 
shadow Text Formatter provides a full 
range of formatting functions, plus 
advanced features such as combining of 
files into one document, variables in text 
(for form letters), and output character 
translation (for printers using nonstan- 
dard character sets). 

The program is written in UCSD 
Pascal and works on systems using 
either North Star 5-inch floppy disks or 
IBM format 8-inch floppy disks. It is 
available from Merrimack Systems, POB 
5218, Redwood City CA 94063, for $99. 
Circle 462 on inquiry card. 



APL for the 8080, 8085, 
and Z80 

Softronics APL has most of the func- 
tions and operators of full APL, in- 
cluding n-dimensional inner and outer 
product, reduction, compression, general 
transpose, reversal, take, drop, execute 
and format, system functions and 
variables, and system commands. It runs 
under the CP/M operating system, 
residing in 30 K bytes of memory. In 
addition to standard ASCII mnemonic 
representations, it supports typewriter 
and bit-pairing ASCITAPL character 
sets. The shared variable mechanism 
allows CP/M disk input and output. 
Softronics APL comes with an optional 
driver program for video display with 
programmable character generator. It is 
priced at $350 on disk, with a user's 
manual. For more information, contact 
Softronics, 36 Homestead Ln, Roosevelt 
NJ 08555. 



Double-Sided Dual Disk 
Drive 

The Micro Squared M-250 unit is 
capable of single or double density and 
consists of two double-sided drives, a 
power supply, cable, and chassis. It has 
140 tracks, with a capacity of 358 K 
bytes of memory. The double-density 
feature allows 875 K bytes of memory 
storage. The unit also features a write 
protect sensor, time erase timing circuits 
internal to the disk drive, and has a sen- 
sor that stops the spindle drive motor 
rotation when no disk is installed. The 
unit costs $1195 and is available from 
Micro Squared Inc, Suite 5B, 7131 
Owensmouth Ave, Canoga Park 
CA 91303. 

Circle 463 on inquiry card. 



Pertec Introduces 8-Inch, 
20 M Byte Winchester 
Drive 

This new drive will use a limited 
motion, 50 ms average access rotary 
positioner. The Mini-VVini can perform 
diagnostic routines without the help of 
the central processing unit by creating a 
bidirectional bus interface using a 6801 
microprocessor. The Mini-Wini has the 
same physical dimensions, mounting 
scheme and voltage requirements as 
floppy disk drives, but offers more 
storage space than floppy disks. The 
price is $3000 and is available from 
Pertec Computer Corp, 9600 Irondale, 
Chatsworth CA 91311. 

Circle 464 on inquiry card. 



February 1980 © BYTE Publications Inc 213 



What's New? 



SOFTWARE 



North Star List Processor 

HELPB5 is a collection of subroutines 
which use dynamic memory assignment 
to perform list processing. The user can 
create a sequential set of array elements 
which describe objects. By filing sets on 
and removing sets from various lists, 
complex processes can be simulated. 
Available subroutines include Create, 
Destroy, File First, File Last, File 
Ranked — which places an entity on a 
sorted list based on the value of a 
selected array element — Remove First, 
Remove Last, and Remove. Four debug- 



ging routines allow the user to print all 
the objects on a list, determine if a par- 
ticular object is on a specified list, if an 
array element has a specified value, and 
print the array elements for a particular 
entity. 

HELPB5 is written in North Star 
BASIC and needs a minimum of 32 K 
bytes of programmable memory. The 
price is $48, including a user's manual 
and sample simulation program. Contact 
American Planning Corp, 4600 Duke St, 
Suite 425, Alexandria VA 22304. 
Circle 465 on inquiry card. 



NEVADA COBOL for 
Microcomputers 

NEVADA COBOL translates source 
language programs into machine 
language on 8080, Z80 and 8085 
microprocessors. Designed for small 
businesses using microcomputers, it 
features random access file support; 
sequential files, both fixed and variable 
length; debugging capability; copy state- 
ment; character string, 16-bit binary and 
packed decimal (COMP-3); 18-bit 
accuracy; hexadecimal non-numeric 



literals; and an interactive 
ACCEPT/DISPLAY. The compiler, 
which is a subset of ANSI-74, generates 
programs at a rate up to 650 lines per 
minute on an 8080-based system. 
Operating under Processor Technology's 
operating system (PTDOS), the compiler 
requires a minimum of 32 K bytes of 
programmable memory. The NEVADA 
COBOL Programmers Reference Manual 
is available for $25 and the Diskette is 
$275, from Ellis Computing, 1480 17th 
Ave, San Francisco CA 94122. 

Circle 466 on inquiry card. 



Library Cross-Reference 
for Floppy Disks 

The CATALOG system provides a 
means to index up to 200 single- or 
double-density 5-inch floppy disks. 
Using the alphabetical lists of files pro- 
duced by CATALOG, any program or 
data file can be located in a few 
seconds. The name, extension, size, date 
and disk number for each file is listed in 
each of three reports. These reports are 
organized by the date within extension 
within name, extension within name 
within disk number, and date within 



name within extension. A list of disks is 
provided after each use of the 
CATALOG program. The program runs 
on 8080 or Z80 microprocessors with 
48 K bytes of memory, floppy disk, 
video display and printer. The program 
requires CP/M with Microsoft MBASIC 
or MITS/Pertec Disk Extended BASIC. 
The SORT System is required for use of 
CATALOG. The CATALOG System is 
priced at $95 and is available from the 
Software Store Ltd, 706 Chippewa Sq, 
Marquette MI 49855. 

Circle 467 on inquiry card. 



6809 Systems Software 

Technical Systems Consultants Inc, 
POB 2574, W Lafayette IN 47906, has 
developed software which includes a 
6809 version of the popular FLEX disk 
operating system, a text editor, a resi- 
dent assembler, BASIC interpreter, and 
an assembly language debug package. 
Most software written for 6800 FLEX 
can be reassembled for 6809 by changing 
any equates into FLEX to the proper ad- 
dresses. FLEX features dynamic file 
allocation, random and sequential files, 
printer spooling, batch job type program 
entry, automatic space compression, 
user start-up facility, and English error 



messages. The resident 6809 assembler 
accepts 6809, 6800, and 6801 mnemonics 
so that existing software can be im- 
mediately reassembled to produce 6809 
object code. 

FLEX is available for the SwTPC disk 
systems on a 5- or 8-inch floppy disk. 
The other software is available on a 
standard 5- or 8-inch FLEX disk which 
may be used on any soft-sectored 6809 
FLEX disk system. Cassette versions are 
available for all but FLEX. Including the 
text editor and assembler, the FLEX 
package is $90. The BASIC interpreter is 
$65, and the debug package is $75. 
Circle 468 on inquiry card. 



Six Software Programs for 
Apple Users 

These six programs from Williamsville 
Publishing require an Apple II with 
32 K bytes of programmable memory, 
one disk drive, Disk II, Applesoft II in 
read-only memory (ROM) on a firm- 
ware card. The programs include Book 
Library; Record Library; Malum II. ..Im- 
perial Roman Programmable Computer 
By Command of Caesar, which takes 
the Latin equivalent of BASIC com- 
mands and uses Roman numerals for 
numeric input and output; Graphics 
Game; Checkbook Program; and Page 
Processor. 

Individual disks sell for $19.95 from 
Williamsville Publishing Co, POB 250, 
Fredonia NY 14063. 

Circle 469 on inquiry card. 



Software for Radio and 
Television Stations 

Solar Computer Systems Corp, 2360 
43rd Ave E, Suite 308, Seattle WA 
98112, has a series of software programs 
designed to run on Smoke Signal Broad- 
casting's Chieftan Systems that are of in- 
terest to radio and television stations. 
Available programs include audience 
measurement, attitude research, music 
research, lifestyle surveys, ARBITRON 
analyses and more. Information is 
available upon request. 

Circle 470 on inquiry card. 



Math Program Performs 
Symbolic Operations for 
Algebra, Trigonometry, 
and Calculus 

This symbolic mathematics system 
enables users to solve polynomial 
multiplications, symbolic differentiations 
and integrations, simplification of 
trigonometric expressions, and exact 
solutions of nonlinear equations. The 
muMATH-79 programs run on 8080, 
8085, and Z80 systems using TRSDOS, 
standard CP/M, or upward compatible 
operating systems such as Cromemco 
CDOS, or IMSAI IMDOS. The program 
is useful for engineers and scientists in 
checking or deriving lengthy analytical 
data. It is also useful for artificial in- 
telligence applications as well as for 
students and teachers in math education. 
The price for the package is $190. For 
more information, contact The Soft 
Warehouse, POB 11174, Honolulu 
HI 96828. 

Circle 471 on inquiry card. 



214 February 1980 © BYTE Publications Inc 




Single Board Computer 
Supports Pascal 




DOSC Inc, 500 Fifth Ave, New York 
NY 10033, has announced its TCB-85 
single board microcomputer capable of 
supporting CP/M and Pascal. The 64 K 
board is compatible with Intel's 
Multibus and features a dual-density 
floppy disk controller that supports up 
to tour disk drives or two double-sided 
disks, video display controller with up 
to 80 characters by 25 lines, RS-232 
serial input/output (I/O) port, parallel 
printer interface, scanned keyboard in- 
terface, vectored interrupts, and three 
timers. 

The price is $1500 per unit. 

Circle 472 on inquiry card. 



Versatile Business Manager 
System 

This system includes a Versatile 4 
Dual Drive computer, a Texas 
Instruments 810 RO Tractor Feed 
Printer, application software for 
business, and a movable table. The 
business software includes a General 
Ledger, Accounts Payable and 
Receivable, Inventory, Person- 
nel/Payroll, and Labor Job Cost 
Analysis. The system is priced at under 
S8500 and is available from CDS Inc, 
Building 3, Drummond Plaza, 
Newark DE 19711. 

Circle 473 on inquiry card. 



Compucolor II System 

Compucolor Corp, POB 569, 
Norcross GA 30071, has developed three 
models of the Compucolor II. Model 3 
has 8 K bytes of programmable 
memory, the Model 4 has 16 K bytes, 
and the Model 5 provides 32 K bytes of 
memory. The Compucolor II uses an 
8080A microprocessor and includes 16 K 
bytes of read- only memory. One 
RS-232C serial port is provided for a 
printer or modem. The Compucolor II 
features a keyboard that is separate 




SYSTEMS 



Hewlett-Packard 
Introduces Personal Com- 
puter for Professionals 

The HP-85 is a complete computer 
system designed for use in business and 
industry by engineers, scientists, 
accountants, and investment analysts. It 
can also be used in the home by hob- 
byists and as an instructional computer 
in secondary schools, colleges, and 
universities. 

The system features a video display, 
thermal printer, tape cartridge, and 
graphics capability in a package the size 
of a typewriter. It is equipped with four 
input/output (I/O) ports to allow the 
user to expand the system to include 
plotters, printers, disk drives, and other 
peripherals that are already on the 
market. 

The HP-85 comes with 16 K bytes of 
programmable memory and can be 
expanded to 32 K by plugging an op- 
tional memory module into one of the 
ports on the back of the machine. The 
graphics display is useful to engineers 
for plotting functions and for test 
analysis, and to business persons to plot 
statistics. The display on the screen can 
be easily printed out on the built-in 
printer. 

The system has a 5-inch, high- 
resolution, black and white video 
display with 16 lines of display and 32 
characters per line. The thermal printer, 
which operates in both alphanumeric 




and graphics modes, prints two 
32-character lines per second. The HP-85 
tape drive uses HP Data Cartridges, 
which have a capacity of 200 K bytes, 
and feature a tape directory that enables 
the system to automatically find exact 
tape locations of recorded programs and 
data. 

The HP-85 measures 41 by 46 by 15 
cm (16 by 18 by 6 inches), and weighs 
9.06 kg (under 20 pounds). It comes 
with a user's manual and a standard 
application software package that con- 
tains 15 programs. The price of the 
HP-85 is $3250. For more information, 
contact Inquiries Manager, Hewlett- 
Packard Co, 1507 Page Mill Rd, Palo 
Alto CA 94304. 

Circle 474 on inquiry card. 



8086 and 8088-Based 
Microcomputers 

Microbyte, 2499 Cerritos Ave, Signal 
Hill CA 90806, has introduced two 
16-bit 8086 and 8088 microprocessor- 
based computers with real-time clock, 
priority vectored interrupts, four port 
serial input and output (I/O) board that 
supports four terminals, 32 K bytes of 
programmable memory, dual-density 
floppy disk controller that supports up 
to four drives with direct memory ad- 



dress (DMA) data transfer, video 
display and keyboard, 19-slot 
backplane, and an interrupt switch-on 
from console to allow re-boot of the 
system without register destruction. The 
systems use Microbyte DOS86 batch 
operating system software and also 
feature 4 K bytes of programmable 
memory on-board, 24 operand address- 
ing modes, three programmable timers, 
and more. The approximate prices for 
the 8086 and 8088 are $4000 and $3900, 
respectively. 

Circle 475 on inquiry card. 



from the processor and video display 
unit. The video terminal has erase-line 
and erase-page commands; two 
character sizes; fifteen plot modes; local, 
full, and half duplex modes; full cursor 
control; and other functions. The 
system uses Disk BASIC 8001 with an 
interpreter in read-only memory. 
Twenty-nine statement types, three com- 
mand types, nineteen mathematical 
functions, and nine string functions are 
included. 

One 5-inch floppy disk is built into 



the main unit. The capacity for each 
side of a 5-inch disk is 51.2 K bytes. 

The video display features eight colors 
with 32 lines and 64 characters per line. 
The usable screen area is 23 cm 
(9 inches) wide by 17 cm (6.75 inches) 
high. Compucolor has developed soft- 
ware for the system including games, 
small business applications, home 
finance, and other programs. The prices 
for the three models are $1495, $1695, 
and $1995. 

Circle 476 on inquiry card. 



February 1980 '- BYTE Publications Inc 215 



PUBLICATIONS 



Short Form Catalog of 
Modems and Accessories 




This six-page catalog contains Racal- 
Vadic's 1200 bits per second (bps) full- 
duplex acoustic coupler; the "50" series 
of direct connect modems; and the 
VA3467 triple modem which emulates a 
Racal-Vadic VA3400 series modem, a 
Bell 212A, or a Bell 103. Other products 
include Bell-compatible 300 bps, 1200 
bps half-duplex, and 2400 bps modems; 
CCITT compatible modems; automatic 
dialers; and a Multiline Automatic Call- 
ing System, which can handle up to 60 
modems for each dialing port. For fur- 
ther information, contact Racal-Vadic, 
222 Caspian Dr, Sunnyvale CA 94086. 
Circle 477 on inquiry card. 



Introduction to VLSI 
Systems 

Introduction to VLSI Systems, by 
Carver Mead and Lynn Conway, deals 
with the theory and practice of design- 
ing, fabrication, and implementing of 
silicon chips, and it provides detailed 
coverage of the underlying physics to 
complete very large-scale integration 
(VLSI) digital computer systems. In- 
troduction to VLSI Systems is suitable as 
a textbook and reference book for 
graduate and undergraduate courses. 

The book is available from Addison- 
Wesley Publishing Co, Reading MA 
01867, for $25.95. 

Circle 478 on inquiry card. 



Sharp APL Reference 

Manual 

This text is complete with illustrations 
and examples, and it discusses the 
features of Sharp APL in terms 
understandable by beginners and profes- 
sional programmers alike. Some of the 
topics reviewed are syntax of APL, 
event trapping, primitive functions and 
operations, structure of data, shared 
variables, report formatting, batch APL, 
and line editing in Sharp APL. The 
manual is available for $18 from 1 P 
Sharp Associates Ltd, 145 King St W, 
Toronto, Ontario M5H 1J8, CANADA. 
Circle 479 on inquiry card. 



Communication Fiber- 
optics Short Form Catalog 




Valtec Corp's catalog, which includes 
their optical fibers and cables, fiberoptic 
modems and interfaces, and baseband 
video links, covers every application 
from computer terminal connections to 
long-haul telephone and CATV flunk- 
ing. 

To obtain a copy of the catalog, write 
Valtec Corp, Communication Fiber- 
optics, 99 Hartwell St, West Boylston 
MA 01583. 

Circle 480 on inquiry card. 



1979 Mapping Collection 
from Harvard Library of 
Computer Graphics 

This six volume collection has been 
structured to give an organization every 
kind of information it may need about 
computer mapping. The collection 
features works on management's use of 
maps; natural resource and environmen- 
tal applications; urban, regional, and 



state applications; computer mapping in 
education; mapping software and car- 
tographic data bases; thematic map 
design; and sections on cadastral 
systems and use of satellite derived data. 
The cost is $45 for the first volume, and 
$30 for each additional selection. The 
complete six volume set is $150. Contact 
the Laboratory for Computer Graphics, 
Harvard University, 48 Quincy St, 
Cambridge MA 02138. 

Circle 481 on inquiry card. 



Publication for the Ohio 
Scientific Challenger IP 

Getting Started With Your Challenger 
IP introduces the fundamentals of C1P 
BASIC and explains its characteristics, 
limitations, and useful features. This 
document discusses calculator and pro- 
gram mode, input and output, data 
representation, and program storage on 
cassette. It also describes ClP control 
and logic, including testing and branch- 
ing, subroutine use, and logical opera- 
tions. This beginner's workbook con- 
tains exercises and sample programs. It 
is available from dealers or by writing 
to TIS, POB 921, Los Alamos NM 
87544. The price is $5.95 plus $1 for 
postage and handling. 

Circle 482 on inquiry card. 



Microprocessor User's 
Guide 

The Microprocessor User's Guide con- 
tains articles written by engineers for 
other engineers and corporate managers 
with a production-oriented, problem 
solving approach in mind. The 78-page 
booklet focuses on designing with 
microprocessors; engineering design 
approach to microprocessors; micro- 
processor architecture; analysis of 6800, 
8080/8085 and Z80 architectures; and 
analysis of single-chip microprocessors. 
Pro-Log's STD BUS, a bus structure for 
8-bit microprocessors, is examined in 
detail. 

The guide is available at no charge 
from Pro-Log Corp, 2411 Garden Rd, 
Monterey CA 93940. 

Circle 483 on inquiry card. 



Using a Programmable 
Calculator Instead of a 
Central Computer 

Providing techniques for using 
calculators in the HP-67/97 or TI-59 
families, the Handbook oj Electronic 
Design and Analysis Procedures Using 
Programmable Calculators offers pro- 
grams and programming techniques for 
solving problems in network analysis, 
active and passive filter design, high fre- 
quency amplifier design, and engineering 
mathematics. Documentation including 
flowcharts, algorithms, sample pro- 
blems, tips, and references clarify many 
aspects of problem solution. The book is 
available for $26.50, from Van Nostrand 
Reinhold Electrical/Computer Science 
and Engineering Series, 135 W 50th St, 
New York NY 10020. 

Circle 484 on inquiry card. 



216 February 1980 © BYTE Publications Inc 



GPIB Controller Im- 
plements IEEE 488 Bus and 
RS-232 Standard 




The Model 609 GPIB Controller can 
be used in place of programmable 
calculators, microcomputers, or as in- 
telligence for a data collector logger 
system. Programs in BASIC enter in 
4 K bytes of programmable memory, 
then are transferred to an internal pro- 
grammable read-only memory (PROM). 
This eliminates the tape loading routines 
and insures that, when the controller is 
turned on, the program is present and 
ready. The Model 609 has control 



features such as serial or parallel poll 
and reception of binary-coded decimal 
(BCD) or ASCII messages, the ability to 
be transparent in a large system, and a 
front panel pass/fail test system. The 
front panel contains all connectors and 
controls and has been designed to 
eliminate inadvertent false operation. 
The unit costs $1395. For more informa- 
tion, contact Physical Data Inc, Dept 
37, 8220 SW Nimbus Ave, Beaverton 
OR 97005. Circle 485 on inquiry card. 



National Introduces New 
Addition to One Chip 
Data Acquisition System 
Family 




Available in two versions, the 
ADC0808 and ADC0809 complementary 
MOS (CMOS) integrated circuits 
incorporate the essential elements of a 
microprocessor-compatible data- 
acquisition system onto a single chip, 
including an 8-bit analog-to-digital 
(A/D) converter, an 8-channel 
multiplexer and microprocessor- 
compatible control logic. The 
ADC0808/09 uses a successive 
approximation conversion technique 
with a high-impedance chopper 
stabilized comparator which makes the 
device virtually immune to temperature, 
long term drift, and input offset errors, 
and it provides effective and accurate 
conversion while running on only 15 
milliwatts. A 256R voltage ladder 
network approach was chosen to 
guarantee against missing codes. 
Resolution is 8 bits, and the 
ADC080809 can perform a conversion 
in 100 microseconds. Latched and 
decoded address inputs and outputs 
make possible interfacing to the 8080, 
8085, Z80, 6800, and National's 8060 
SC/MP microprocessor, among others. 

For more intormation on prices and 
availability, contact Keith Mueller, 
National Semiconductor, 2900 Semicon- 
ductor Dr, Santa Clara CA 95051. 
Circle 486 on inquiry card. 



Magnetic Bubble Mass 
Storage for DEC 
Microcomputers 







This new LSI-11 -compatible bubble 
memory system is comprised of a dual 
height controller module (designated 
Bubbl-Board MBC-11) and one or more 
dual height bubble memory modules 
(designated Bubbl-Pac MBB-11). The 
MBC-11 controller contains its own 8-bit 



microprocessor and is capable of con- 
trolling up to 16 MBB-11 bubble 
memory modules. The microprocessor 
handles bubble device formatting and 
control, as well as interfacing the bubble 
memory system to the LSI-11 bus struc- 
ture. The controller maps standard 
floppy disk track and sector addresses 
into bubble device page addresses, so 
that the bubble memory is fully com- 
patible with all DEC software for the 
LSI-11, including the mass storage 
operating systems such as RT-11. The 
bubble memory system appears just like 
a floppy disk to the processor, though 
with much faster access time. Data 
storage is absolutely nonvolatile. Each 
MBB-U bubble memory module uses 
one LSI-11 chassis slot and contains 46 
K bytes of storage. Access time to the 
first data byte averages less than 7 ms. 

The MBC-11 is priced at $650 and the 
MBB-11 at $950. Contact Bubbl-Tec, 
3120 Crow Canyon Rd, San Ramon CA 
94583. Circle 487 on inquiry card. 



The Ruler That Thinks 

The Panasonic Electronic Ruler Com- 
puter uses a small displacement measur- 
ing wheel to directly measure lengths, 
distances, areas, and volumes, in linear, 
square, or cubic units, in any scale, 
from any document. A multifunction 
calculator is integrated in the ruler per- 
mitting measured data to be used 
automatically in computations. Inter- 
mediate measurements can be stored in 
the calculator's memory to yield a total 
quantity. The computer displays values 
directly in millimeters, centimeters or 
meters, and converts to either inches or 
feet simply by pressing a function key. 
The Electronic Ruler-Computer can 
measure any regular or irregular surface, 
such as curved walls, floors, containers, 
etc. Documents to be measured need not 
be in original scale; variations caused by 
reduction or enlargement can be pro- 
grammed into the computer with results 
automatically displayed in the original 
scale. 

Additional features include ad- 
dressable memory; metric and area con- 




version; percent, add-on, and discount 
computations; automatic square rool 
and 7r; floating decimal point system; 
mixed calculations, and more. 

The Electronic Ruler/Computer is 
priced at $99.95. For further informa- 
tion, contact the distributors, Chafitz 
Inc. 1055 First St, Rockville MD 20850. 
Circle 488 on inquiry card. 



February 1980 © BYTE Publications Inc 217 




Whsl'sPJew? 



MISCELLANEOUS 



S-100 Communications 
Board 




Designed specifically for S-100 ap- 
plications, Inco's six port EIA/RS-232 
board, based on the Zilog Z80A, 
features synchronous and asynchronous 
communications at a wide range of data 
rates. The board also contains two real- 
time clocks programmable in several 
modes, and meets the proposed IEEE 
S-100 standards. It performs hardware 
cyclic redundancy check (CRC) genera- 
tion and checking, and provides stan- 
dard protocol support. The board, 
documentation and a software guide are 
available for $895 from Inco Inc, 7916 
Westpark Dr, McLean VA 22102. 
Circle 489 on inquiry card. 



Floppy Disk Controller 
Board for the TM990 




A floppy disk controller compatible 
with the TM990 series of microcomputer 
board products has been announced by 



Texas Instruments Inc, FOB 1433, MS 
6404, Houston TX 77001. The 
TM990/303 board supports up to four 
double-sided drives. The board is pro- 
grammable for data encoding formats 
and number and types of disk drives. 
The TM990/303 has the ability to inter- 
face to single- and dual-density drives. 
The controller is compatible with IBM 
3740 and TI disk formats. Data transfer 
format and steppermotor rates are both 
programmable. In addition, the con- 
troller also features write precompensa- 
tion, soft-sector compatibility, internal 
phase acquisition, and address mark 
detection. The board is priced at $845. 
Circle 490 on inquiry card. 



MC6809 Microprocessor 
Development Systems 



«\. 




Motorola has announced six update 
packages to adapt a user's previous 
EXORciser I, IA, or II systems to 
MC6809 system design. These products 
enable designers to develop and debug 
any system centered around this power- 



ful eight-bit microprocessor. The new 
EXORciser II and EXORterm 220 differ 
from the MC6800 units in current pro- 
duction in that they contain a 
microprocessing module with a M6809 
component complement, as well as 
extending the capabilities of other inter- 
nal modules to MC6809 specifications. 
EXORciser and EXORterm systems can 
be upgraded to permit M6809 designs by 
adding an MC6809 microprocessing 
module, a DEbug module, a floppy-disk 
controller, programmable read-only 
memory (PROM) firmware, and an 
MC6809 MDOS floppy disk, containing 
a macroassembler and video editor. By 
updating these units for operation with 
the MC6809 modules, the features of 
EXORciser II, such as dynamic systems 
bus, dual memory map, memory parity, 
second-level interrupt vectors, and 
more, are achievable. 

The prices for the updating systems 
are $3200. The prices for the complete 
MC6809-based EXORciser and 
EXORterm development systems range 
from $7900 to $9365. For additional 
information, contact Motorola Inc, 
POB 20912, Phoenix AR 85036. 
Circle 491 on inquiry card. 



Power Saver from Power 
Dynamics 




Power Dynamics has developed a 
single output open frame switcher. The 
unit measures 7 by 10 by 23 cm (2.75 by 
4 by 9 inches). It is available in all the 
standard output voltages from 5 to 48 
volts. The price is $175. For more infor- 
mation, contact Power Dynamics Corp, 
9421 Telfair Ave, Sun Valley CA 91352. 
Circle 492 on inquiry card. 



Device for Remote Control 
of Electrical Devices 




Introl/X-10 allows Apple users to 
remotely control 110 V AC devices by 
commands sent through a BSR/System 
X-10 Command Console over existing 
building wiring. The unit comes with 
software to control devices on predeter- 
mined schedules. It provides for selec- 
tion of daily or weekly schedules, 
specification of the exact date for a par- 
ticular event, specification of intervals of 
time for an event, and, for energy 
management, device wattage ratings for 
power consumption accounting. The 
system consists of the Introl Controller 
board with timer and ultrasonic 
transducer, the BSR/X-10 Command 
Console, and three Remote Modules for 
$279. The Introl/X-10 Controller Card 
costs $189 and additional remote 
modules are available for $15. For more 
information, contact Mountain Hard- 
ware Inc, 300 Harvey West Blvd, 
Santa Cruz CA 95060. 

Circle 493 on inquiry card. 



218 February 1980 '- BYTE Publications Inc 



32 K Byte Static Memory 
Boards for 6800/6809 




Gimix, 1337 W 37th PI, Chicago IL 
60609, is delivering a fully static 32 K 
byte programmable memory board for 
use with the SS-50 (6800) and SS-50C 
(6809) bus. The board features four 
independently dip-switch addressable 8 
K byte blocks. Each block can be 
addressed to any 8 K boundary or dis- 
abled. The board is capable of decoding 
the tour additional address lines of the 
SS-50C bus to allow memory decoding 
up to 1 M bytes. The switches enable or 



disable the extended addressing and set 
it to one of sixteen possible banks. The 
board is designed for high noise immu- 
nity. The price of the full 32 K board is 
$548.15. The 16 K version costs $328.12 
and 24 K version costs $438. 14. Both 
can be expanded to contain up to 32 K 
bytes of memory. 

Circle 510 on inquiry card. 



Lowercase and Keyboard 
Modification Kit for 
TRS-80 

This kit includes wire, solder, control 
key, 2102 memory device, slide switch, 
mounting hardware, and documenta- 
tion. The low power 2102 memory part 
is connected to a slide switch that allows 
the TRS-80 to be used with or without 
lowercase letters. To minimize the 
chance of damage to the 2102, its con- 
necting wires have been pre-assembled. 
The control key has gold-plated contacts 
for long life and can be easily mounted 
on the keyboard. The kil is priced at 



Low Power, 32 K Pro- 
grammable Memory for 
Heath H8 Computers 

A board with 32 K bytes of program- 
mable memory, using less than 6 W of 
power and compatible with current 
Heath peripherals, is available from D-G 
Electronic Developments Co, 3223 Forest 
Ln, Garland TX 75042. Other features 
include circuit protection to prevent 
damage to memory output buffers if two 
blocks are assigned to the same address 
space, memory addressing controlled by 
a dual in-line (DIP) switch, and it is 
arranged as four independently 
addressable 8 K byte blocks with 
transparent refresh. The price for the 
board is $479, and it comes fully 
assembled and tested. 

Circle 511 on inquiry card. 



$19.95, and is available from Emmanuel 
B Garcia Jr and Associates, 3950 N Lake 
Shore Dr, Rm 2310, Chicago IL 60613. 
Circle 512 on inquiry card. 




FREE! 



Axiom EX-801 PETPrinter(withgraphics)$ 475.00 

Axiom EX-820 PET Plotter $ 749.00 

Anderson Jacobson 841 Selectric ... $1015.00 

Leedex Video 100 12" Monitor $ 119.00 

HeathWH19Terminal(factoryasm.) ...$ 770.00 

Heath WH 14 Printer (factory asm.) ... $ 735.00 

IEEE-RS232PrinterAdaptorforPET... $ 88.00 



Up to $170 in merchandise with purchase 
of one of following PET-CBM items ! ! ! 



BETSI PET to S-100 Interface $ 119.00 

PET Connectors-Parallel or IEEE $ 1 .95 

Cassette Port $ 1.45 

Hands on Basic with a PET $ 9.45 

Programming the 6502 (Zaks) $ 9.45 

6502 Applications Book (Zaks) $ 10.45 

6500 Manuals (MOS Technology) .... $ 6.50 

Programming a Microcomputer: 6502 . $ 8.45 
6502 Assembly Language 

(Osborne) NEW! $ 8.10 

All Books and Software 1 5% Off 

CBM Word Processor for PET -Machine Language 
Auto Scroll, insert, delete, form letter append, etc. 
8K Version $24.00 16Kor32K with disk $89.00 

Cassettes {all tapes guaranteed) AGFA PE61 1 
Premium quality, high out put lownoise in 5 screw 
housing with labels: 
C-10 10/5.65 50/25.00 100/48.00 
C-30 10/6.90 50/30.00 100/57.00 



PET SPECIALS *FREE 

PET 16N 16K full size graphics keyboard $995 $130 

PET 16B 16K full size business keyboard $ 995 $130 

PET 32N 32K full size graphics keyboard $1 295 $1 70 

PET 32B 32K full size business keyboard $1295 $170 

PET 8N 8K full size graphics keyboard $ 795 $100 

PET 2040 DUAL DISK DRIVE-343,000 bytes $1295 $170 

PET 2022 Tractor Feed Printer $ 995 $1 30 

PET 2023 Pressure Feed Printer $849 $110 

PET C2N External Cassette Deck $ 95 $ 12 

Used 8K PETs (limited quantities) $ 495 

*Amount of Free Merchandise with Purchase 
of PET-CBM Item. 



K1M-1 $159 (add $30 for power supply) SYM-1 $209 

BAS-1 Microsoft ROM Basic for SYM $ 85 

Memory Plus (KIM, SYM, AIM) $195 

SYM Assembler in ROM $ 85 

SEA-1 6 New 1 6K Static RAM $325 

Seawell Motherboard - 4K RAM Space ... $139 

KTM-2/80 Synertek Video Board $349 

S-100 16K Static RAM Kit SALE $219 

TIS PET Workbooks - set of 6 $ 21 .50 

Dust Cover for PET $ 8.90 



ATARI -INTRODUCTORY SPECIAL 

ATARI 400. Alan 800 and all Atari Modules 20% OFF. 



Programmers Toolkit - PET ROM Utilities . $ 44.90 

Sargon II (TRS-80 or Apple) NEW! $ 24.90 

MicrochessforPET(PeterJennings) ....$ 17.90 

PET 4 Voice Music System $ 29.90 

4 Voice Music Monitor for PET $ 1 5.90 

CmCWordProcessorprogramforPET. . . $ 25.00 

Adventures by Scott Adams 1 5% Off 




SALE 



3M "Scotch" 8" Disks 1 0/$31 .00 

3M "Scotch" 5" diskettes ... 1 0/$31 .50 

Verbatim 5" diskettes 10/$26.50 

Diskette Storage Pages 10/$ 3.95 

Disk Storage Boxes 8" $2.85 514" $1.95 
(Write for quantity prices) 



2716 EPROM (5 volt) $ 39 

6550 RAM (for 8K PET) $ 1 2.70 

6502 $9.75 6522 $9.00 6520 $5.50 

2114L450ns$5.35 24® $4.95 1 00 @ $4.45 




1 1 5 E. Stump Road 
Montgomeryville, PA 1 8936 



(215)699-8386 
699-5826 



A B Computers 



MINIMAX 

by COMPU/THINK 

MINIMAX I (.8 Megabyte Disks] $4495 
MINIMAX II (2.4 Megabyte Disks) $5995 

SPECIAL— MINIMAX prices include Compu/ 
Think PAG EMATE Database and Report Writer at no charge. 

The most advanced complete microcomputer system available. 

Includes CPU, 12" CRT, Full Keyboard, 2 Quad-Density Disk 
Drives, 2 Megahertz 6502 Hybrid Processor {double speed), 1 08 
K System Memory, High Resolution (512 x 240) Graphics, 
Programmable Character Fonts, Microsoft Extended BASIC, 
DOS with Random Access I/O, Full Complement of I/O Ports, 
Monitor with Debug, Trace, and Tiny Assembler, Fifth (PL/M and 
Forth combination) Interpreter, Complete editing and entry with 
split screen capability, 64 Microprogrammable Opcodes, Bus- 
iness software (with Database) available. 



WRITE FOR COMPLETE CATALOG 

Add $1 .00 per order for shipping. 

We pay balance of UPS surface charges on all prepaid orders. 



Circle 237 on inquiry card. 



February 1980 © BYTE Publications Inc 219 



What's New? 



MISCELLANEOUS 



tiny FORTH 2.1 for TRS-80 

The Software Farm, FOB 2304, 
Reston VA 22090 has developed the 
tinyFORTH 2.1 system for TRS-80 
systems. Programs written in 
tinyFORTH can run faster and use less 
memory than similar programs in 
BASIC because tinyFORTH includes a 



compiler in addition to an interpreter. 
This system includes a powerful text 
editor, a Z80 assembler, and a graphics 
package. The tinyFORTH system 
occupies 8 K bytes of memory and 
comes with cassette tape and documen- 
tation for 16 K Level II TRS-80s. The 
system costs S29.95. 

Circle 500 on inquiry card. 



32 K Structured BASIC 

Cromemco 32 K Structured BASIC, 
which runs in 64 K Cromemco Systems, 
assists a programmer in building a pro- 
gram from logical blocks of code. This 
facilitates program development and 
reduces debugging and maintenance of 
programs. It contains all features of 
16 K BASIC plus long variable names of 
up to 31 characters, statement labels 
that replace statement numbers to 
reference lines in a BASIC program, an 



in-line BASIC editor, a keyed sequential 
access method (KSAM), procedures, and 
control structures including if . . . then 
. . . else. while . . . endwhile, and repeat 
. . , until. 

Cromemco 32 K Structured BASIC is 
available for use on Cromemco systems 
on 8-inch or 5-inch floppy disks for 
$295. For additional information, con- 
tact Cromemco Inc, 280 Bernardo Ave, 
Mountain View CA 94043. 

Circle 501 on inquiry card. 



Motorola Introduces 
MC68000 Design Module 

Motorola has introduced the 
MEX68KDM, an MC68000 design 
module. The MEX68KDM permits easy 
chip evaluation, using either an EXOR- 
ciser development system or an IBM370 
or PDPII, in conjunction with cross- 
computer software. For system emula- 
tion, the module includes 32 K bytes of 
programmable memory, two 16-bit 
parallel input/output (I/O) ports, three 
16-bit programmable timers and two 
serial RS-232 ports. 

MEX68KDM includes MACSbug, a 
powerful 16-bit microprocessor debugg- 
ing tool. Once a memory file is resident 
in programmable memory, a user may 



begin his program debugging. The 
memory map for the MEX68KDM 
allows for the use of any of the on-card 
I/O and additional external memory or 
I/O. A 6800 bus interface card is pro- 
vided to allow the MEX68KDM to read 
or write data to an external memory or 
I/O card. The design module may be 
used in a stand-alone mode, in an 
EXORciser development system in the 
nonexpanded bus mode, or in a card 
cage with standard 6800 memory. 

The design module with two RS-232 
cables is priced at $1795. Contact 
Motorola Semiconductor Inc, POB 
20912, Phoenix AZ 85036, for more in- 
formation. 

Circle 502 on inquiry card. 




PROSYS I System 

Aimed primarily at the process con- 
trol and industrial /measurement 
markets, the system allows a process 
control engineer or technician to com- 
municate with a digital computer- 
controlled process system. PROSYS I 
includes the ADAC System 1000 
enclosure with the 64 K byte version of 
the Digital Equipment Corp LSI-11/2 
microcomputer, dual-port serial inter- 
face, single drive, double-density floppy 
disk and video terminal. The software 
resides in less than 32 K bytes of 
memory. The software includes an 
operating system. The system can 
accomodate up to eighteen PROSYS I 
optional modules. The price lor the 
system is $14,000, and it is available 
from ADAC Corp, 70 Tower Office 
Park, Woburn MA 01801. 

Circle 503 on inquiry card. 



Multiuser Operating 
System for Micropolis 
Microdisk 




Micropolis Corp, 7959 Deering Ave, 
Canoga Park CA 91304, is marketing 
their fully integrated rigid disk sub- 
system which includes their 8-inch rigid 
disk drive with up to 31.2 M bytes ol 
formatted data storage capacity, an 
intelligent disk adapter-interface card, 
and a software package for microcom- 
puter systems that use the S-100 bus. 
The Microdisk subsystems are available 
in capacities of 6.2, 18.7 and 31.2 M 
bytes and are expandable by daisy 
chaining. Up to three add-on modules 
may be connected to a master unit. 
Prices for the Microdisk system begin at 
under $5000. 

Circle 504 on inquiry card. 



S-100 16-Channel 12-Bit 
Analog to Digital 
Converter Board 




The Tecmar S-100 Analog to Digital 
(A/D) board interfaces the Analogic MP 
6812 Complete Data Acquisition System 
to the S-100 bus. The board accepts six- 
teen single ended inputs and has data 
rates up to 30 kHz with twelve bit 
accuracy. The total of multiplex settling 
time and sample-hold acquisition time is 
about 7 microseconds. The board pro- 
vides two's complement right-justified 
outputs and variable voltage ranges. The 
board may be configured to act as an 
input/output (I/O) device or to act as a 
memory mapped device. The board 
requires little software. The price is 
$495, and it is available from Tecmar 
Inc, 23414 Greenlawn Ave, Cleveland 
OH 44122. 

Circle 505 on inquiry card. 



220 February 1980 © BYTE Publications Inc 




af 8 New? 



MISCELLANEOUS 



Network Information 
Resource 

The SOURCE is a computer-based 
electronic message and information 
system. It allows users to send messages 
over computer terminals via a nation- 
wide switching network. The SOURCE 
provides advanced electronic mail 
features such as text editing, scanning, 
delayed delivery, interactive conversa- 
tion, and bulletin boards. It also acts as 
an information supermarket offering 
news, educational programs, travel and 
shopping services, and much more. To 
use the SOURCE, subscribers need only 
a microcomputer or terminal. The cost 
of the service is $100 initial registration 
fee plus $2.75 an hour. The service is 
$15 an hour between 7 AM and 6 PM, 
Monday thru Friday. For information, 
contact Telecomputing Corp of 
America, 1616 Anderson Rd, McLean 
VA 22102. 

Circle 506 on inquiry card. 



S-100 Card Adds Sound 

Two General Instrument AY-3-8910 
programmable sound generators are 
interfaced to the S-100 bus on the 
Noisemaker to create sounds and noises. 
The board provides six tone generators, 
two noise sources, two envelope gen- 
erators and four 8-bit input/output 
ports. Sound effects and noises may be 
created and added to graphics and com- 
puter games. An on-board audio ampli- 
fier and breadboard area allows 
inclusion of the board into any system. 
The Noisemaker is available now as an 
unpopulated, solder masked and screen- 
ed, printed circuit board for $34.95. 
Contact Ackerman Digital Systems, 
Suite 208, 110 York Rd, Elmhurst IL 
60126. 

Circle 507 on inquiry card. 



Double-Density Floppy 
Disk Interface 




Tarbell Electronics has released its 
new interface board, which is supplied 
with the BASIC INPUT/OUTPUT 
SYSTEM software for CP/M on single- 
density floppy disk, permitting users to 
mix single- and double-density disks. As 



many as four drives can be selected, 
using either single- or double-density. 
The 8-inch, Shugart-compatible disk in- 
terface contains phase-lock-loop and 
write precompensation, and the 
bootstrap programmable read-only- 
memory (PROM) is disabled on comple- 
tion of the bootstrap operation, freeing 
all 64 K bytes of memory for other use. 
Extended addressing capability provides 
eight additional address bits as specified 
by the new IEEE standard, allowing 
direct transfers to and from any location 
within a 16 M byte address range. The 
interface comes with BIOS for CP/M on 
floppy disk for $425 from Tarbell Elec- 
tronics, 950 Dovlen PI, Suite B, 
Carson CA 90746. 

Circle 508 on inquiry card. 



Package Turns Exidy 
Sorcerer into Z80 
Development System 




Available for $99, a software package 
called the Development Pac can turn an 
Exidy Sorcerer into a sophisticated, 
cassette-based, Z80 development system. 
The package includes four modules: a 



designer's debugging tool (DDT), a line- 
oriented text editor, a relocating 
assembler, and a linking loader. All can 
operate with the Sorcerer's dual cassette 
interface to allow tape-based system 
development. The system supports 
global symbols for intermodule com- 
munication and allows the user to define 
the input/output (I/O) devices for 
source code, object code, and listings. 
The debugging tool allows the user to 
display and modify any programmable 
memory location or any Z80 register. 
Using the Development Pac, a program- 
mer can design a program that is far 
larger than the Sorcerer's memory 
without having to worry about size 
limits, due to partitioning of memory 
and two predefined buffers that can be 
used for program storage. The package 
is available from Exidy Data Systems, 
2599 Garcia Ave, Mountain View CA 
94043. 

Circle 509 on inquiry card. 




8086 Boards 

CPU with $650. 

Vectored Interrupts 
PROM-I/O $495. 

RAM $395. 

8K x 16/16K x 8 



ANALOG Boards 

A/D 16 Channel, $495. 
12 Bit, High Speed 

D/A 4 Channel, $395. 
12 Bit, High Speed 





VIDEO 
DIGITIZATION 

Real Time Video $850. 
Digitizer and Display 
Computer Portrait 
System $4950. 



S-100 Boards 

Video and/or Analog 
Data Acquisition 
Microcomputer Systems 



EC RR 



SNC. 



The High Performance S-100 People 

TECMAR, INC. 

23414 Greenlawn • Cleveland, OH 44122 
(216) 382-7599 



February 1980 © BYTE Publications Inc 221 



TRS-80 ES 
SERIAL I/O 

• Can input into basic 

• Can use LLIST and 
LPRINT to output, or 
output continuously • 
RS-232 compatible • 
Can be used with or 
without the expansion 
bus • On board switch 
selectable baud rates 
of 110, 150,300,600, 
1200, 2400, parity or 
no parity odd or even, 
5 to 8 data bits, and 1 
or 2 stop bits. D.T.R. 
line • Requires +5, 
-12 VDC • Board only 
$19.95 Part No. 8010, 
with parts $59.95 Part 
No. 801 OA, assembled 
$79.95 Part No. 8010 
C. No connectors pro- 
vided, see below. 




EIA/HS-232 



DB25P $6.00. wich 
9'. 8 conductor 
cable S10.95 Part 
No. DB25P9 



3' nbbon cable 
with attached con- 
nectors to fitTRS- 
80 and our serial 
boacdS19.95Part 
No. 3CAB40. 



RS-232/ TTL 
INTERFACE 

• Converts TTL to RS- 
232, and converts RS- 
232 to TTL • Two sep- 
arate circuits • Re- 
quires -12 and +12 
volts • All connections 
go to a 10 pin gold 
plated edge connector f 
kit $ 9.95 Part No. 
232A 10 Pin edge 
connector $3.00 Part 
No. 10P, 






** 



MODEM 

• Type 1 03 • Full or 
half duplex • Works up 
to 300 baud • Origi- 
nate or Answer • No 
coils, only low cost 
components • TTL in- 
put and output-serial 

• Connect 8 fi speak- 
er and crystal mic. 
directly to board • 
Uses XR FSK demod- 
ulator • Requires +5 
volts • Board only 
$7.60 Part No. 109, 
with parts$29.95Part 
No. 109A 




DISKETTES 



Verbatim 



Box of 10, 5" $29.95, 
8" $39.95. 
Plastic box, holds 10 
diskettes, 5" - $4.50, 
8" -$6.50. 



RS-232/TTY 
INTERFACE 

This board has two 
active circuits, one 
converts RS-232 to 
20mA, and the other 
converts 20mA to 
RS-232. Requires 
+12 and -12 volts. 
$9.9 5 Part No. 600A 
Kit. 




S-100 BUS 
ACTIVE TERMINATOR 

Board only $14.95 Part No. 900. with parts 
$24.95 Part No. 900A 





apple ii-::- 

SERIAL I/O 
INTERFACE 



Baud rate is continuously adjustable from 
to 30,000 • Plugs into any peripheral 
connector • Low current drain. RS-232 input 
and output • On board switch selectable 5 to 
B data bits, 1 or 2 stop bits, and parity or no 
parity either odd or even • Jumper selectable 
address • SOFTWARE • Input and Output 
routine from monitor or BASIC to teletype or 
other serial printer • Program for using an 
Apple II for a video or an intelligent terminal. 
Also can output in correspondence code to 
interface with some selectrics. • Also 
watches DTR • Board only $1 5.00 Part No. 
2, with parts $42.00 Part No. 2A, assembled 
$62.00 Part No. 2C 



8K EPROM piiceon 

Saves programs on PROM permanentlytuntil 
erased via U V light) up to 8K bytes. Programs 
may be directly run from the program saver 
such as fixed routines or assemblers. • S- 
100 bus compatible • Room for 8K bytes of 
EPROM non-volatile memory (2708's). • On- 
board PROM programming • Address 
relocation of each 4K of memory to any 4K 
boundary within 64K ■ Power on jump and 
reset jump option for "turnkey" systems and 
computers without a front panel • Program 
saver software available • Solder mask both 
sides • Full silkscreen for easy assembly. 
Program saver software in 1 2708 EPROM 
$25. Bare board $35 including custom coil, 
board with parts but no EPROMS $1 39, with 
4 EPROMS $179, with 8 EPROMS $219. 




WAMECO PRODUCTS 
WITH 
ELECTRONIC SYSTEMS PARTS 
FDC-1 FLOPPY CONTROLLER BOARD will 
drive shugart, pertek, remex 5" & 8" drives 
up to 8 drives, on board PROM with power 
boot up, will operate with CPM (not 

included). PCBD $42.95 

FPB-1 Front Panel. (Finally) IMSAI size hex 
displays. Byte or instruction single step. 

PCBD $42.95 

MEM-1A BKxB fully buffered, S-100, uses 
2102 type RAMS. 

PCBD $24.95, $1 68 Kit 

QMB-12 MOTHER BOARD, 13 slot, termi- 
nated, S-1 00 board only $34.95 

$89.95 Kit 
CPU-1 8080A Processor board S-1 00 with 
8 level vector interrupt PCBD . . $25.95 
$89.95 Kit 
RTC-1 Realtime clock board. Two independ- 
ent interrupts. Software programmable. 
PCBD ......... 

EPM-1 1702A 4K EPROM 



are 
SE 



card PCBD $25.95 

$49.95 with parts less EPROMS 

EPM-2 2708/2716 16K/32K 

EPROM card PCBD $24.95 

$49.95 with parts less EPROMS 

QMB-9 MOTHER BOARD. Short Version of 

QMB-12. 9 Slots PCBD $30.95 

$67.95 Kit 

MEM-2 16Kx8 Fully Buffered 2114 Board 
PCBD $25.95, $269.95 Kit 



T.V. 
TYPEWRITER 

• Stand alone TVT 

• 32 char/line, 16 
lines, modifications for 
64 char /line included 

• Parallel ASCII (TTL) 
input • Video output 

• 1 K on board memory 

• Output for computer 
controlled curser • 
Auto scroll • Non- 
destructive curser • 
Curser inputs: up, down, 
left, right, home, EOL, 
EOS • Scroll up, down 

• Requires +5 volts 
at 1.5 amps, and -12 
volts at 30 mA • All 
7400, TTL chips • 
Char. gen. 2513 • 
Upper case only • 
Board only $39.00 
Part No. 106, with 
parts $145.00 Part 
No. 106A 




UART& 
BAUD RATE 
GENERATOR 

• Converts serial to 
parallel and parallel to 
serial • Low cost on 
board baud rate gener- 
ator • Baud rates: 
110, 150, 300, 600, 
1200, and 2400 • 
Low power drain +5 
volts and -12 volts 
required • TTL com- 
patible • All characters 
contain a start bit, 5 
to B data bits, 1 or 2 
stop bits, and either 
odd or even parity. • All 
connections go to a 44 
pin gold plated edge 
connector • Board only 
$12.00 Part No. 101, 
with parts $35.00 Part 
No. 101 A, 44 pin edge 
connector $4.00 Part 
No. 44P 




TAPE 
INTERFACE 

• Play and record Kan- 
sas City Standard tapes 

• Converts a low cost 
tape recorder to a 
digital recorder • Works 
up to 1200 baud •Dig- 
ital in and out are TTL- 
serial • Output of 
board connects to mic. 
in of recorder • Ear- 
phone of recorder con- 
nects to input on board 

• No coils • Requires 
+5 volts, low power 
drain • Board only 
$7.60 Part No. 111, 
withparts$29.95Part 
No. 111A 




HEX ENCODED 
KEYBOARD 

E.S. 
This HEX keyboard 
has 1 9 keys, 1 6 encod- 
ed with 3 user defin- 
able. The encoded TTL 
outputs, 8-4-2-1 and 
STROBE are debounced 
and available in true 
and complement form. 
Four onboard LEDs 
indicate the HEX code 
generated for each 
key depression. The 
board requires a single 
+5 volt supply. Board 
only $15.00 Part No. 
HEX-3, with parts 
$49.95 Part No. HEX- 
3A. 44 pin edge con- 
nector $4.00 Part No. 
44P. 




DC POWER SUPPLY 



• Board supplies a regulated +5 
volts at 3 amps., +1 2, -1 2, and -5 
volts at 1 amp. • Power required is 
8 volts AC at 3 amps., and 24 volts 
AC C.T. at 1.5 amps. • Board only 
$12.50 Part No. 6085, with parts 
excluding transformers $42.50 
Part No. 6085A 




Tn QrHpr ■ Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order. 
' We accept C.O.D. orders in the U.S. only, or a VISA or Master Charge no., expiration date, signature, phone no., 
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han- 
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line [408] 448-0800 



Send for FREE Catalog ... a big self-addressed envelope with 41 * postage gets it fastest! 



ELECTRONIC SYSTEMS De P { - B p - °- Box 21638, SanJose, CAUSA 95151 



222 BYTE February 1980 



COMPUCRUISE 

Put a computer in 
your car, which gives 
you the most effec- 
tive and functional 
cruise control ever 
designed, plus com- 
plete trip computing, 
fuel management sys- 
tems, and a remark- 
able accurate quartz 
crystal time system. 
So simple a child can 
operate, the new 
CompuCruise com- 
bines latest computer 
technology with 

state-of-the-art re- 
liability in a package 
which will not likely be 
available on new cars 
for years to come • 
Cruise Control • Time, 
E.T. , Lap Timer, Alarm 
•Time, Distance, Fuel 
to Arrival • Time, Dis- 
tance, Fuel to Empty • 
Time, Distance and 
Fuel on Trip • Current 
or Average MPG, 
GPH •Fuel Used, Dis- 
tance since Fillup • 
Current and Aver- 
age-Vehicle Speed • 
Inside, Outside or 
Coolant Temperature 
• Battery Voltage • 
English or Metric 
Display. £169.95 , 
without cruise con- 
trol $129.95. 




i: E 



FLOPPY DISK 
STORAGE BINDER 

This black vinyl 
three-ring binder 
comes with ten 
transparent plastic 
sleeves which ac- 
commodate either 
twenty, five-inch or 
ten, eight-inch floppy 
disks. The plastic 
sleeves may be or- 
dered separately and 
added as needed. A 
contents file is in- 
cluded with each 
sleeve for easy iden- 
tification and organiz- 
ing. Binder & 10 hol- 
ders $14.95 Part No. 
BBDO; Extra holders 
95* each. Part No. 
800 




OPTO-ISOLATED 

PARALLEL INPUT 

BOARD FOR 

APPLE II 

There are 8 in- 
puts that can be dri- 
ven from TTL logic or 
any 5 volt source. The 
circuit board can be 
plugged into any of 
the 8 sockets of your 
Apple II. It has a 16 pin 
socket for standard 
dip ribbon cable con- 
nection. 

Board only £15.00. 
Part No. 120, with 
parts £69.95. Part 
No. 120A. 




TIDMA 

•Tape Interface Direct 
Memory Access • Re- 
cord and play programs 
without bootstrap load- 
er (no prom) has FSK 
encoder/decoder for 
direct connections to 
low cost recorder at 
1200 baud rate, and 
direct connections for 
inputs and outputs to 
a digital recorder at 
any baud rate • S- 1 00 
bus compatible • Board 
only £35.00 Part No. 
112, with parts £110 
Part No. 112A 




SYSTEM 
MONITOR 

8080, 80B5, or Z-BO 
System monitor for use 
with the TIDMA board. 
There is no need for the 
front panel. Complete 
with documentation 

S12.95. 



16KEPROM 

Uses 2708 EPROMS, 
memory speed selec- 
tion provided, ad- 
dressable anywhere in 
65K of memory, can 
be shadowed in 4K in- 
crements. Board only 
$24.95 part no. 
7902, with parts less 
EPROMs $49.95 part 
no. 7902A. 




ASCII KEYBOARD 

TTL & DTL compatible • Full 67 key array 

• Full 128 character ASCII output • Positive 
logic with outputs resting low • Data Strobe 

• Five user-definable spare keys • Standard 
22 pin dual card edge connector • Requires 
+5VDC, 325 mA. Assembled & Tested. 
Cherry Pro Part No. P70-05AB. £1:19.95. 




ASCII KEYBOARD 

53 Keys popular ASR-33 format • Rugged 
G-10 PC. Board • Tri-mode MOS encoding 
• Two-Key Rollover • MOS/DTL/TTL Compat- 
ible • Upper Case lockout • Data and Strobe 
inversion option • Three User Definable 
Keys • Low contact bounce • Selectable Par- 
ity • Custom Keycaps • George Risk Model 
753. Requires +5, -12 volts. £59.95 Kit. 



ASCII TO CORRESPONDENCE 
CODE CONVERTER 

This bidirectional board is a direct replace- 
ment for the board inside the Trendata 1 000 
terminal. The on board connector provides 
RS-232 serial in and out. Sold only as an 
assembled and tested unit for £229.95. 
Part No. TA1000C 



DISK JACKET" 

Made from heavy duty 
.0095 matte plastic 
with reinforced 

grommets. The mini- 
diskette version holds 
two 5-1/4 inch disk- 
ettes and will fit any 
standard three ring 
binder. The pockets to 
the left of the disk- 
ette can be used for 
listing the contents of 
the disk. Please order 
only in multitudes of 
ten. £9.95/10 Pack. 




ATARI 800 

Computer with BK 
£995.00, disk drive 
£549.00, printer 
$599.99 




VIDEO TERMINAL 

1 6 lines, 64 columns • 
Upper and lower case 

• 5x7 dot matrix • Se- 
rial RS-232 in and out 
with TTL parallel 
keyboard input • On 
board baud rate 
generator 75, 110, 
150. 300, 600, & 
1200 jumper select- 
able • Memory 1024 
characters (7-21 L02) 

• Video processor chip 
SFF96364 by Necu- 
lonic • Control char- 
acters (CR, LF, -♦, <-, 
t, i, non destructive 
cursor, CS, home, CL 

• White characters on 
black background or 
vice-versa • With the 
addition of a key- 
board, video monitor 
or TV set with TV 
interface (part no. 
107AJ and power 
supply this is a com- 
plete stand alone 
terminal • also S-100 
compatible • requires 
+ 16, & -16 VDC at 
100mA, and BVDCat 
1A. Part No. 1000A 
£199.95 kit. 



RS-232/20mA 
INTERFACE 

This board has two 
passive, opto-isola- 
ted circuits. One con- 
verts RS-232 to 
20mA, the other con- 
verts 20mA to RS- 
232. All connections 
go to a 10 pin edge 
connector. Requires 
+12 and -12 volts. 
Board only $9,95, 
part no. 7901, with 
parts $14.95 Part 
No. 7901A. 




COMPUCOLORII 

Model 3, 8K $13 95, 
Model 4, 16K $14 95, 
Model 5, 32K£16 95. 
Prices include color 
monitor, computer, 
and one disk drive. 



n 



L 



PET COMPUTER 

With 16K S. monitor - 
£ 795. Dual Disk 
Drive- £10 95 




^nppfcz 



APPLE II PLUS 

16K - £975, 32K - 
$1059, 48K - £1123. 
Disk&cont. £589 



CASSETTE TAPE 
ERASER 




REMOVES RECORD- 
INGS IN ONE SEC- 
OND! The process 
eliminates static pos- 
itive / negative ions 
and maintains original 
tone quality with min- 
imal tape hiss • To im- 
prove tone quality • To 
reduce hissing • For 
quick and easy to 
erase • No battery or 
liquid required • Pow- 
erful and effective ac- 
tion • Unconditional 2 
year guarantee. 

ERASER-8 £19.95. 



1SK RAMS 

For the Apple, 
TRS-80 or Pet $8 
each Part No. 41 16/ 
2117. 



APPLE II HOBBY/ 

PROTOTYPING 

CARD 

$14.95 Part No. 
7907 



T.V. INTERFACE 

• Converts video to 
AM modulated RF, 
Channels 2 or 3. So 
powerful almost no 
tuning is required. On 
board regulated power 
supply makes this ex- 
tremely stable. Rated 
very highly in Doctor 
Dobbs' Journal. Recom- 
mended by Apple • 
Power required is 12 
volts AC C.T., or +5 
volts DC • Board only 
£7.60 part No. 107, 
with parts £1 3.50 Part 
No. 107A 





PARALLEL TRIAC 

OUTPUT BOARD 

FOR APPLE II 



This board has 8 tnacs capable of 
switching 110 volt 6 amp loads (660 watts 
per channel) or a total of 5280 watts. Board 
only £15.00 Part No. 210, with parts 
£119.95 Part No. 210A. 



TA r\rriar • Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order. 
' We accept C.O.D. orders in the U.S. only, or a VISA or Master Charge no., expiration date, signature, phone no., 
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han- 
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line [408] 448-0800 



Send for FREE Catalog ... a big self-addressed envelope with 41 * postage gets it fastest! 



ELECTRONIC SYSTEMS 



P. 0. Box 21638, San Jose, CA USA 95151 



Circle 164 on inquiry card. 



BYTE February 1980 223 



Circle 165 on inquiry card. 



Hie IMBl-TRANS 1000 



A completely refurbished , ' 
IBM Selectric Terminal \vitli 1 ™ 
built-in ASCII Interface. 




&&?i 



■ 



Features: 



$1495 



300 Baud 

14.9 characters per second 

printout 

Reliable heavy duty Selectric 

mechanism 

RS-232C Interface 

Documentation included 

GO day warranty -parts and 

labor 

High quality Selectric printing 

Off-line use as typewriter 

Optional tractor feed available 

15 inch carriage width 



SERIAL I/O 

Four Serial I/O RS- 
232 ports, S-100 
Bus, Software or 
jumper selectable 
baud rates (110, 300, 
BOO, 1200. 2400, 
4800, 9600. 19.2K), 
on board Xtal baud 
rate generator, Ad- 
dressing, switch 
selectable, Parity or 
no parity (odd or even) 
switch selectable, 1 or 
2 stop bits, 5 to 8 
bits/character. Board 
only $29.95, Part No. 
7908. With parts (kit) 
$199.95, Part No. 
7908A. 



HOW TO ORDER 
DATA-TRANS 1000 

1. We accept Visa, Master 
Charge. Make cashiers checks or 
personal check payable to: 

DATA-TRANS 

2. All orders are shipped 
F.O.B. San Jose, CA 

3. Deliveries are immediate 




For orders and information 



DATA-TRANS 

2154 OToole St. 

UnitE 

San Jose, CA 95131 

Phone: (408) 263-9246 





TTL parallel, TTL serial. RS232C serial. 20 
mil loop serial. Quiet, clean — no ribbons or 
ink; 24 characters/second; Upper/lower case 
96 ASCII characters; Signalling rates: Serial 
Mode — 1 1 or 300 Baud; Parallel mode — up 
to 960 characters/second; For applications 
over 48 columns, automatically prints on next 
line; Prints 1 character at a time — ideal for 
interactive applications; Local line feed for 
advancing paper; Parity check (odd, even or 
none); ASCII control codes: back space, car- 
riage return, line feed (implemented as a new 
line), vertical tab (1 line), negative vertical tab 
(on receipt of ESC, VT), Bell (9 microsecond 
pulse on receipt of BEL) PS-4BC Printer 
$699, with Keyboard, $895. Paper roll 
5Vs"x164' $3.00 



44 BUS MOTHER 
BOARD 

Has provisions for ten 
44 pin (.156) connec- 
tors, spaced 3/4 of an 
inch apart. Pin 20 is 
connected to X, and 
22 is connected to Z 
for power and ground. 
All the other pins are 
connected in parallel. 
This board also has 
provisions for bypass 
capacitors. Board 
cost $15.00 Part No. 
102. Connectors 

$3.00 each Part No. 
44WP. 




GAME PADDLES 

& SOUND 
For Your TRS 80 
(Level II or Disk) 




Includes: 2 game pad- 
dles, interface, soft- 
ware, speaker, power 
supply, full documen- 
tation including: sche- 
matics, theory of 
operation, and user 
guide; plus 2 games on 
cassette (Pong and 
Starship War). $79.95 
Complete Part No. 
7922C 



LEEDEX 
MONITOR 



CI 

12" Black and White* 
12 MHz Bandwidth 
• Handsome Plastic 
Case«$139.00 



DIGITAL 
CASSETTE 




5 min. each side. Box 
of 10 $9.95. 



Tq Qrfjpr ■ Mention part no. description, and price. In USA shipping paid by us for orders accompanied by check or money order. 
We accept C.O.D. orders in the U. S. only, or a VISA or Master Charge no., expiration date, signature, phone no., 
shipping charges will be added. CA residents add 6.5% for tax. Outside USA add 10% for air mail postage and han- 
dling. Payment must be in U. S. dollars. Dealer inquiries invited. 24 hour order line [408] 448-0800 



Send for FREE Catalog ... a big self-addressed envelope with 41* postage gets it fastest! 



ELECTRONIC SYSTEMS DeptB P0 - Box 21638, San Jose, CAUSA 95151 



224 BYTE February 1980 



Circle 164 on inquiry card. 



i 



Dial: 402-987 



ill/ Ill/Ill 7 i 




LINE 



i 



YOU NEED CRISP, HIGH CONTRAST 
BUCK-WHITE and VIVID COLOR 
ALPHA-NUMERICS/GRAPHICS 
'capabilities FROM YOUR VIDEO 
MONITOR IF YOU WANT REALLY 
SUPER-LOOKING IMAGES FROM 
YOUR COMPUTER 



AS SPECIALISTS IN VIDEO 
IMAGING ...we Think we 
have the right monitor or 
modulator tor your system. 
Our product line Includes 
the popular "Micro-Verter" 
(OSI and Apple Inc. approved 
UHF color modulator), a variety 
of color and B-W monitors, color 
cameras, B-W cameras, Audio 
subcarrier kits and parts. FREE 
CATALOG UPON REQUEST. 
Dealers welcomed. Well established 
program with over 400 dealers, 





ATV Research 13-bbroadway Dakota city, ne.bbt3I 



SURPLUS ELECTRONICS 




ASCII 



ASCII 



IBMSELECTRIC 

BASED I/O TERMINAL 

WITH ASCII CONVERSION 

INSTALLED $645.00 

• Tape Drives • Cable 

• Cassette Drives • Wire 

• Power Supplies 12V15A, 12V25A, 
5V35A Others, • Displays 

• Cabinets • XFMRS • Heat 
Sinks • Printers • Components 

Many other items, SEND $ 1 .00 FOR CATALOG 
REFUNDABLE FIRST ORDER 
WORLDWIDE ELECT, INC. 
130 Northeastern Blvd. 
Nashua, NH 03060 

Phone orders accepted using 

VISA or MC 

Call 603-889-7661 



SHORT »50 ft. 
CASSETTES 



At' 1 




s # 


■■• 


50 1 


MKJSOBfcTT* tl> 


m P.*™ 6«Ba™dsC* 


,ws " H 




■ '-.' 





Qty. Price 

1 $1.00 

10 $0.75 

50 $0.65 






Circle 166 on inquiry card. 



Circle 167 on inquiry card. 



Premium tape and cassettes acclaimed 
by thousands of repeat order microcom- 
puter users. Price includes labels, cas- 
sette box and shipping in U.S.A. VISA 
and M/C orders accepted. California 
residents add sales tax. Phone (415) 
968-1604. 



MICROSETTE CO. 

475 Ellis Street 
Mt. View, CA 94043 



Circle 168 on inquiry card. 



SATELLITE 
TRACKING 
SOFTWARE 



SATTRAK INTERNATIONAL 




SATELLITE THANKING 
BASIC anr] FORTRAN A 
Each puirjiam series jj 

1:01: H.M.1E:: PftNGE ■-. 



illow you In operjle your v.vr, r.F'ACF CENTRE and 
The SBfnS SOPHISTICATED ALGORITHMS are in Cold 
rams use EASY INPUTS lr:r thinner nr educational use 
-.5 LATITUDE'LOUGSTUDE'ALIirUDE.'AJ'tMUTHiELEVA- 
irr.N PAST/PRESENT or FUILRE. plug ihnso loalures: 
layl • VISIBLE'ALL PASS opnons 



■ lull SELF TESTrr 



) run'.' or-uralors manual • Handles all tyuns of ornils 

TRAWUPOAT + GRAPHICS lapcclly computer, caSHG-tti! or (lis 
POSMILOOK,'OBS.'UPDAKs|ii;<;.rycnmpulei,c,]=sollr,oroi!.c) 

'JDOC TRAKIPDSIl.LOOK.DICi HI-MAI rii;-;,f.-!ht; (apeci'/ compulcrl 

9000 TRAKiPOSrj iQG'.-G'V. -iphatf M'.c [specify compiileD . 

BOTFL FORTRAN LISTING POSH-LOOK, DBS + 15 SUEROUTItJES 
(with ASCII STANDARD CARD FORMAT. 1200 CARDS) 

30QHL BASIC LISTING iM..t'0'.jii Bnsir.^cpsify compulerl . 



■ i-r(Lt ■■ 



a us ai 



Send cheque/money order to: 
SAT TRAK International 

c/o Computer-land of Colorado Springs 

4543 Tempteton Gap Road 

Colorado Springs CO USA 80909 

Colorado residents add 5% sales tax. 



TRS-80 users 

Learn FORTH 

FORTH is ;i structured high level language thai 
dramatically cuts program development time. You 
can expand the FORTH language by defining new 
operations and data types. FORTH programs arc 
compiled to reduce memory space and speed execu- 



tinyFORTII is a complete version of the powerful 
FORTH language tailored to the TRS-80, The 
tinyFORTH system includes FORTH, a text editor, 
an assembler, graphics, and cassette I/O. 
Learn FORTH on your own computer. 'Hie 
tinyFORTH user's manual contains hundreds of 
examples to teach you FORTH in a hands-on style. 
tinyFORTH lor 16k level II TRS-80: 

Cassette and full documentation $29.95 

Documentation only S 9.95 

All orders are fully guaranteed. And S.I ,50 for 
postage and handling. Order with check, money 
order. Visa, or Maslercharee. 

Write for a FREE booklet describing FORTH. 

The Software Farm 

Reston. VA 221)90 



Dept. A15 



Put 

SARGON IP 

on Disk 

Send a SASE and $5 to: 

RCV Consultants, Dept B 

9459 Taylorsville Road 

Dayton, Ohio 45424 

for complete instructions enabling you to copy your 
Hayden tape to disk. Implementation relocates the 
tape-loaded machine-language code from low to 
high memory during DOS operation, and during 
game-play disables the monitor vectors which 
would point into SARGON II code, thus avoiding 
critical memory conflicts. 

All you have to do is type in and run a 4-statement 
BASIC program, and it does everything necessary 
to make the tape-loaded SARGON II code ready for 
disk storage, retrieval, and game-play. As a bonus, 
you get to keep the DOS 2.2 Keyboard debounce 
feature during SARGON II operation! 

Requires a TRS-80- 1 Model I Level II 32 K with one 
disk drive, and a DOS 2.2 diskette. 

1 Copyright 1979 By Hayden Book Company 
2 Trade Mark of the Tandy Corporation 



Circle 170 on inquiry card. 



Circle 171 on inquiry card. 



THE 
SWITCH 



OPTO ISOLATED 120 VAC 
SOLID STATE SWITCH 

• INPUT 5 VDC 2 MA (TTL) 
. ISOLATION 1500 VDC 

. OUTPUT 6 A 120 VAC 720 W 

• SIZE 2x21 CHANNEL 

• SIZE 2x84 CHANNEL 
PRICE KIT TESTED UNIT 
1 CH. $9.95 $12.50 

4 CH. $34.95 $44.95 

ADD 6% SALES TAX IN CALI- 
FORNIA AND $1.00 SHIPPING 
& HANDLING FOR ORDERS 
LESS THAN $20. ADD 4% FOR 
VISA OR M.C. 

JOHN J. BELL 

P.O. BOX 338 

REDWOOD CITY, CA 94064 

(415) 367-1137 



STATIC RAM CHIPS 

CftPTflDV DDIMC From Hie same shipment we use in our 
rMUIUni rnllYIC professional quality boards. 

2114L450ns.$5.90 200 ns. $6. 90 

4044 450 ns. .$5.90 250 ns. $6. 90 

Add $5.00 Handling on Orders Under $200.00 

32K STATIC RAM BOARD 

OR THE SS50 AND SS50C BUS (SWTP ate.) 

SS50C Extended Addressing (can be disabled) 

• 4 separate 8K blocks. 
Low power 21 14L RAMS (2 AMPS Typical for 32K) 
Socketed for 32K 
Write Protect 

• Gold Bus Connectors 

16K $328.12 

24K $438.14 

32K $548.15 

Phone, write, or see your dealer for details and prices on ou 
broad range of Boards and Systems for the SS50/SS50C bus 
including our UNIQUE 80x24 VIDEO BOARD, and our AC 
Power Control Products for all computers, 

Gimix <& 

1337 W. 37th Place • Chicago, IL 60609 
(312)927-5510 • TWX 910-221-4055 

The Company that delivers. 

Quality Electronic products since 1975. 

GIMIX 1 ' and GHOST- are Registered Trademarks of GIMIX INC 




The best choice 
in mainframes ! 

• S100 CARD FRAME • AXIAL BLOWER 

• 22 MHz 12" CRT MONITOR • ASSEMBLED & TESTED 

• 18 AMP POWER SUPPLY • READY FOR YOUR CARDS 

• UPPER & LOWER CASE • S89-5.00 OEM QUANT. ONE 
ASCII KEY BOARDS 



,D 



OOU I IM F I IM I T 



- (305) 724-1588 



Circle 172 on inquiry card. 



Circle 173 on inquiry card. 



Circle 174 on inquiry card. 



Circle 175 on inquiry card. 



EXCITING MAILORDER DISCOUNTS 




NOVATION CAT 

ACOUSTIC MODEM 

• ANSWER. ORIGINATE 

• 300 BAUD 

• BELL 103 

• LOW PROPILE DESIGN 



s 179 



[00 





Japplc II 16k 

OR APPLE I PLUS 

$975 



APPLE II 32KM050 
APPLE IU8K>1 126 



•COLOR •GRAPHICS •SOUND 
•APPLE II ACCESSORIES* 



APPLE SOFT BASIC CARD M 55 

DC HAYES MICROMODEM '335 

ALF MUSIC SYNTHISIZER '240 

CORVUS 10 MEGABYTE DRIVE '4,650 



APPLE DISK II '440 

WITH CONTROLLER CARD :'; . . .'495 
PASCAL LANGUAGE SYSTEM. .'450 
INTEGER BASIC CARD '155 



SD EXPANDORAM 



•64KS- 100 DYNAMIC RAM BOARD 
•WORKS WITH Z-80. 8080 & 8085 
•POWER CONSUMPTION 5 WATTS 
•BANK SELECT -PHANTOM REFRESH 
•NO WAIT STATES REQUIRED 



WITHOUT MEMORY- 

16KKIT 

32KKII 

48K KIT 

64K KIT 



_$149 00 
— 215 00 
_269 00 
_349 00 
_409 00 




ADD S50 FOR ASSEMBLED & TESTED 



LEEDEX VIDEO 100 

12" BLACK & WHITE MONITOR 

♦VIDEO BANDWIDTH 1 2 MH^ + 3db 
•COMPOSITE VIDEO INPUT 

$12900 

SOROCIQ120 

SERIAL RS232C 

FULL ASCH II UPPER/LOWER CASE 
NUMERIC KEYPAD CURSER KEYS 
SCREEN CONTROLS S7 r no0 
PROTECTED FIELDS 



'750 



'ALSO AVAILABLE' 

SOROC IQ 140 $ 1,225. 00 



•2-80 MICROPROCESSOR 
•30x64 CHARACTER DISPLAY 
•S-IOO COMPATIBLE EXPANDABLE 
•SERIAL AND PARALLEL I 
•DUAL CASSETTE I O 

• 64 USER DEFINABLE CHARACTERS 
•2-10x5 12 HIGH RESOLUTION GRAPHICS 
•RESIDENT 4K MONITOR ROM 

•FULL SIZE ASCII KEYBOARD 

• UPPERLOWER CASE AND NUMERIC KEYPAD 

16K S 99S 32K S 1,145 48K M295 



» TO ORDER * 

Phono orc!<;r:; invited, using credit cards:., Or send cashiers 
chet:k or money order Ihfi! drawi; on a: U;S. bank. Please add 
3% (S10 Mtnimum) : for handling^ shipping 1 (air service) and 
insurance, or equipment wiii be shipped freight collect, 
California residents add 6% safes Sax. All equipment i$:'in 
factory cartons with the manufacturers; warranty. Equipment 
is subject to price change and availability without notice. 




VISA 



mmjm.. mrtMm^- 



.■■■ ' -"•.:. . it- ■ ; 



MEMOREX 

Floppy Discs 

Lowest prices. WE WILL NOT 
BE UNDERSOLD!! Buy any 

quantity 1-1000. Visa Mastercharge 
accepted. Call free (800)235-4137 
for prices and information. All 
orders sent postage paid. 



PACIFIC 
EXCHANGES 

100 Foothill Blvd. 
San Luis Obispo. CA 
93401. (In Cal. call 
(805)543-1037) 




$ MINI FLOPPY AT $ 
$ STORE DISCOUNT $ 

SINGLE SIDED-$225.00 
DOUBLE SIDED-$345.00 

CABINETS- CABLES AND 
POWER SUPPLIES ARE 
ALSO AVAILABLE 

INTERFACE , INC 
20932 CANTARA ST 
CAN0GA PARK,CA 91304 

(213) 341-7914 



81999 
2399 
2765 
2799 
3215 



8000 
1149 



Save More Than 80% 

North Star — Intertube 

Thinker Toys — Microtek 

The Smartest Computers at the Smartest Price 

Quad ft Double Density 

List 
Horizon- 1-32K-D Kit 
Horlzon-2-32K-D Kit 

Assembled & Tested 
Horlzon-2-32K Kit Quad 

Assembled 8c Tested 
Pascal for North Star on Disk 
Powerful North Star BASIC 
ZTBI PT 212 Computer 5 mHz 
Thinker Toys Dlsous/2D A&T 
Dusous/2 + 2 1.2 Megabytes A&T 1549 
Measurement system memory 
A&T 4mHz 64 K 
Godbout Memory Call for price 

Intertube II Smart Terminal 995 745 

Microtek Printer 750 675 

Anadex Printer 995 875 

Florida Data Printer 600 CPS 4300 Call for price 
Maryellen Word Processor Your Best Buy 38 
Textwriter III 

EZ-80 Tutorial Learn Machine Language 
PDS For North Star Better Than CP/M 
Compiler for Horizon Secret Superfast Code 
10% Off Software Prices With Computers 
Verbatim the Best Diskettes Box of 10 
Which Computers Are Best? Brochure. 
North Star Documentation Refundable 
W/HRZ 

American Square Gorapntflrs 
Kivett Dr ' Jamutown NC £7282 
(9191-8B3-110S 



Only 

S1585 

1905 

2195 

2221 

2555 

49 

FREE 

6S50 

949 

1299 

640 



125 
25 
99 

100 

99 

FREE 
20 



Circle 229 on inquiry card. 



Circle 230 on inquiry card. 



Circle 231 on inquiry card. 



226 BYTE February 1980 



Super Color S-100 Video Kit $99.95 

Expandable to 256 x 192 high resolution color 
graphics. 6847 with all display modes computer 
controlled. Memory mapped. 1K RAM expanda- 
ble to 6K. S-100 bus 1802, 8080, 8085, Z80 etc. 

Gremlin Color Video Kit S59.95 

32 x 16 alpha/numerics and graphics; up to 8 
colors with 6847 chip; 1K RAM at E000. Plugs 
into Super Elf 44 pin bus. Not expandable to high 
resolution Graphics. 



Elf II Adapter Kit $24.50 

Plugs into Elf II providing Super Elf 44 and 50 pin 
bus plus S-100 bus expansion (With Super Ex- 
pansion). High and low address displays, state 
and mode LED's optional $18.00. 

1802 16K Dynamic RAM Kit $149.00 

1802/S-100 expandable to 32K, Hidden refresh 
w/clocks up to 4 MHz w/no wait states Addl, 16K 
RAM $79.00. 



Quest Super Basic 

Quest, the leader in inexpensive 1802 systems 
announces another first. Quest is the first com- 
pany worldwide to ship a full size Basic for 1802 
systems. A complete function Super Basic by 
Ron Cenker including floating point capability 
with scientific notation (number range ± . 1 7E 3B ) , 
32 bit integer ±2 billion; Multi dim arrays; String 
arrays: String manipulation; Cassette I/O, Save 
and load, Basic, Data and machine language pro- 
grams; and over 75 Statements, Punctions and 
Operators. 

Easily adaptable on most 1802 systems. Re- 
quires 12K RAM minimum for Basic and user 



programs. Cassette version in stock now. ROM 
versions coming soon with exchange privilege 
allowing some credit for cassette version. 
Super Basic on Cassette S40.00 

Tom Pittman's 1802 Tiny Basic Source listing 
now available. Find out how Tom Pittman wrote 
Tiny Basic and how to get the most out of it. 
Never offered before. $19.00 

S-100 4-Slot Expansion S 9.95 

Super Monitor VI. I Source Listing $15.00 
Coming Soon: Assembler. Editor, Disassem- 
bler, DA/AD, Super Sound/Music, EPROM pro- 
grammer. 




RCA Cosmac Super Elf Computer $106.95 



Compare features before you decide to buy any 
other computer. There is no other computer on 
the market today that has all the desirable bene- 
fits of the Super Elf for so little money. The Super 
Elf is a small single board computer that does 
many big things. It is an excellent computer for 
training and tor learning programming with its 
machine language and yet it is easily expanded 
with additional memory, Full Basic, ASCII 
Keyboards, video character generation, etc. 
Before you buy another small computer, see if it 
includes the following features: ROM monitor; 
State and Mode displays; Single step: Optional 
address displays; Power Supply; Audio Amplifier 
and Speaker; Fully socketed for all IC's; Real cost 
of in warranty repairs; Full documentation. 
The Super Elf includes a ROM monitor for pro- 
gram loading, editing and execution with SINGLE 
STEP for program debugging which is not in- 
cluded in others at the same price. With SINGLE 
STEP you can see the microprocessor chip opera- 
ting with the unique Quest address and data bus 
displays before, during and after executing in- 
structions. Also, CPU mode and instruction cycle 
are decoded and displayed on 8 LED indicators. 
An RCA 1861 video graphics chip allows you to 
connect to your own TV with an inexpensive video 
modulator to do graphics and games. There is a 
speaker system included for writing your own 
music or using many music programs already 
written. The speaker amplifier may also be used 
to drive relays for control purposes. 



A 24 key HEX keyboard includes 16 HEX keys 
plus load, reset, run, wait, input, memory pro- 
tect, monitor select and single step. Large, on 
board displays provide output and optional high 
and low address. There is a 44 pin standard 
connector slot for PC cards and a 50 pin connec- 
tor slot for the Quest Super Expansion Board. 
Power supply and sockets for all IC's are in- 
cluded in the price plus a detailed 127 pg. instruc- 
tion manual which now includes over 40 pgs. of 
software info, including a series of lessons to 
help get you started and a music program and 
graphics target game. 

Many schools and universities are using the 
Super Elf as a course of study. OEM's use it for 
training and research and development. 
Remember, other computers only offer Super Elf 
features at additional cost or not at all. Compare 
before you buy. Super Elf Kit $106.95, High 
address option $8.95, Low address option 
$9.95. Custom Cabinet with drilled and labelled 
plexiglass front panel $24.95. Expansion Cabinet 
with room for 4 S-100 boards $41.00. NiCad 
Battery Memory Saver Kit $6.95. All kits and 
options also completely assembled and tested. 
Questdata, a 12 page monthly software publica- 
tion for 1 B02 computer users is available by sub- 
scription for $12.00 per year. 
Tiny Basic Cassette $10.00, on ROM $38.00, 
original Elf kit board $14.95. 1802 software; 
Moews Video Graphics $3.50. Games and Music 
$3.00, Chip 8 Interpreter $5.50. 



Super Expansion Board with Cassette Interface $89.95 



This is truly an astounding value! This board has 
been designed to allow you to decide how you 
want it optioned. The Super Expansion Board 
comes wilh 4K of low power RAM fully address- 
able anywhere in 64K with built-in memory pro- 
tect and a cassette interface. Provisions have 
been made for all other options on the same 
board and it fits neatly into the hardwood cabinet 
alongside the Super Elf. The board includes slots 
for up to 6K of EPROM (2708, 2758, 271 6 or Tl 
271 6) and is fully socketed. EPROM can be used 
for the monitor and Tiny Basic or other purposes. 
A IK Super ROM Monitor $19.95 is available as 
an on board option in 2708 EPROM which has 
been preprogrammed with a program loader/ 
editor and error checking multi file cassette 
read/write software, (relocatible cassette file) 
another exclusive from Quest. It includes register 
save and readout, block move capability and 
video graphics driver with blinking cursor. Break 
points can be used with the register save feature 
to isolate program bugs quickly, then follow with 
single step. The Super Monitor is written with 



subroutines allowing users to take advantage of 
monitor functions simply by calling them up. 
Improvements and revisions are easily done with 
the monitor. If you have the Super Expansion 
Board and Super Monitor the monitor is up and 
running at the push of a button. 
Other on board options include Parallel Input 
and Output Ports with full handshake. They 
allow easy connection of an ASCI I keyboard to the 
input port. HS 232 and 2D ma Current Loop for 
teletype or other device are on board and if you 
need more memory there are two S-100 slots for 
static RAM or video boards. Also a 1K Super 
Monitor version 2 with video driver for full capa- 
bility display with Tiny Basic and a video interface 
board Parallel I/O Ports $9.85, RS 232 $4.50, 
TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pin 
connector set with ribbon cable is available at 
$15.50 for easy connection between the Super 
Elf and the Super Expansion Board. 
Power Supply Kit for the complete system (see 
Multi-volt Power Supply). 



TERMS: $5.00 min. order U.S. Funds. Calif residents add 6% tax. 
BankAmericard and Master Charge accepted. 
Shipping charges will be added on charge cards. 



Same day shipment. First line parts only 
Factory tested. Guaranteed money back 
Quality IC's and other components at fac- 
tory prices. 

INTEGRATED CIRCUITS 



.66 



7400TTL 

7400N 

74 02^ 

74 04 "J 

7409M 

74 ION 

74I4N 

7420N 

7422N 

7430N 

7442N 

7445N 



7475N 
7-IB5N 
7 .ISBN 
7490N 
7492N 
7493N 
7495N 



741 SON 
74151N 
74 1 5-1 N 

74157N 
74161N 
74162N 
741G3N 
74174N 
74175N 
741 SON 
741S2N 
741S3N 
74221 N 
742S8N 
743ESN 
743fc"6N 
7 4 367 N 



74LS0O TTL 

74LS00N .35 

74LS02N .35 

74LS04N .35 

74LS05N .35 

74LS08N 35 

74LS1DN 35 

74LS13N 55 

74LS14N 1 10 

74LS20N 35 

74LS22N 35 

74LS28N 41 

74LS30N 35 

74LS33N .75 

74LS3SN .55 

74LS74N 1 25 

74LS7SM 1.00 

74L390N .05 

74LS93N .70 

74LS95N 1.10 

74LS107N 45 

74LS112fJ 45 

74LS113N 35 

74LS132N 89 

74L5136N 45 

74LS151N S5 

74LS15SN 85 

74LS157N .85 

74LS162N 1.15 

74LS163N 1 15 

74LS174N 2 00 

74LS190N 1.06 

74LS221N 1.95 

74LS258N .67 

741.S367N 1.35 

LINEAR 

CA3045 ,90 

CA3046 1 10 

CA30B1 1.60 

CA30B2 1.90 

CA3089 2 95 
LM301AN'AH 35 

LM305H 87 

LM307N .35 

immn .69 

LM309K 150 

LM3MH/N .90 

LM317T/K 3.75 

LM318 1.35 

LM320K-5 150 




P.O. Box 4430X Santa Clara, CA 95054 

fc. For will call only: ( 40f ») 988 - 164 ° 
Ik 2322 Walsh Ave. ^ 

yc/t_ 



LM323K-5 5 95 
LM32QK-12 1.50 
LM32QK-15 150 

LM320T-5 1 60 
LM320T-8 1 60 
LM320T-12 150 
LU320T-15 1 60 
LM324N 1 15 
LM339N 1 55 

LM340K-5 1 35 
LM340K-8 135 
LM340K-12 1 35 
LM340K-15 1 35 
LM340K-24 1 35 
LM340T-5 1 25 
LM340T-8 1 25 
LM340T-12 1 25 
LM34QT-15 1 25 
LM340MB 1 25 
LM340T-2.1 1 25 
LM343H 4.50 
LW350 
LM370 
LM377 
LM379 
LM380N 
LM381 
LM3B2 
I M703H 
LM709H 
.M723H/N 
LM733N 

M74 1 CH 
IM741N 

M747H/H 
. M74BN 

Ml 303:'! 
IM1304 
LM1305 
LM1307 
.M1310 
I.MI458 
IM1800 
LM1812 



ELECTRONICS 



.15 



RESISTORS H wait 5°, 

10 per type 03 1000 per lype 012 
25 per type 025 350 piece pack 
100 per type 015 5 per lype 6.75 

ft wall $% per type .05 

KEYBOARDS 

55 key ASCII keyonarrl kit S67.50 

Fully assembled 77.50 

53 Hey ASCII keyboard kil 60 00 

fully assembled 70.00 Enclosure 14 95 

LEDS 

Red T018 

Green, YdIIow T018 

Jumbo Red .20 

Green. Orange. Yellow Jumbo 25 

Cllpllte LED Mourning Clips ESI 25 

(specify reil. amber, green, yellow, clear! 

CONTINENTAL SPECIALTIES In stock 
Complete line of breadboard test equip 

MAX- 100 B dlgll Freq. Clr. SITE. 95 



SPECIAL PRODUCTS 

MM5B65 Stopwatch Til 

PC board 

Swllches Mom Pushb' 



_3pos 



itide 



Encoder HD0165-5 
3 Digit Universal 
Counter Board XII 

Operates 5- IB Voll DC lo 5 

ryp. 125" LED display II 
Paralronlcs 1G0A Logic 
Analyzer KM S22. 

Model 10 Trigger 

Expander Kit S22I 

Model 150 Bus 

Grabber K.| $36! 

Sinclair 3') Oigll 

Multimeter SB! 

Clock .:. : ■■ Kll S2; 

2,5 MM/ Frequency Counter 

KM S3 

30 MHi Frequency Caualer 



12 V 



t 300 rr 



12.6V CT 600 ma 

12V 250 ma wall plug 

12V CT 250 m a ajII plug 

24V CT 400 ma 

10V 1 2 amp wall plug 

12V 6 amp 

12V 500 ma wall plun 



12V 1 



ii pi«g 



12V 3 amp wall plug 
DISPLAY LEOS 



MAM 

MAN3 

MAN72/74 

DL704 

DL7O7/DL707R 

DL727'728 

DL747/750 

DL750 

FND3S9 

FNO50O/5O7 

FHD503/510 

FNO80O/8O7 

3 digit Bubble 

4 digit Bubble 
DD8 Fiuoresccnl 
DG10 Fluorescent 

5 digit 14 pm display 
NSNG9 9 rJifjH display 
7520 Clairex photocell:; 
TIL3I1 Hex 
MAN3640 
MAN; i. Hi 
MAfM6-Ifi 

MAN4710 

M AN- 17.10 
MANf'Mu 
'/ANL710 
UArjiiMii 
MA1002A 
MA1012A 
102P3 Iranslormer 



CA .270 2.90 

CC .125 39 

CA/CA 300 1 00 

CC 300 1 25 

CA 300 1 00 

CAyCC .500 1 90 

CA'CC 600 1 95 

CC 600 1.95 

CC .357 .70 

CC.'CA .500 1 35 

CC/CA .500 .90 

CC/CA .1 



.60 



CC 56 

CA .60 
CC 60 



ROCKWELL AIM 65 Computer 

6502 based single board with full ASCII keyboard 
and 20 column thermal printer. 20 char, al- 
phanumeric display, ROM monitor, fully expand- 
able. S375.00. 4K version $450.00. 4K Assem- 
bler $85.00, 8K Basic Interpreter $100.00. 

Special small power supply for AIM 65 assem . in 
frame $49.00. Complete AIM 65 in thin briefcase 
with power supply $485.00. Molded plastic 
enclosure to fit AIM 65 plus power supply $47.50. 

AIM 65/KIM/VIM/Super Elf 44 pin expansion 
board; 3 female and 1 male bus. Board plus 3 
connectors $22.95. 

AIM 65/KIMA/IM I/O Expansion Kit; 4 parallel 
and 2 serial ports plus 2 internal timers $39.00. 
PROM programmer for 2716 $150.00. 



Multi-volt Computer Power Supply 

8v 5 amp, ±18v .5 amp, 5v 1 .5 amp, -5v 
.5 amp, 12v .5 amp, -12 option. =:5v, ±12v 
are regulated. Kit $29.95. Kit with punched frame 
$37.45, $4.00 shipping. Woodgrain case 
$10.00, $1.50 shipping. 



PROM Eraser 

Will erase 25 PROMs in 15 minutes. Ultra- 
violet, assembled S37.50 



60 Hz Crystal Time Base Kit $4.40 

Converts digital clocks from AC line frequency 
to crystal time base. Outstanding accuracy. 



79 IC Update Master Manual $35.00 

Complete IC data selector, 2500 pg. master refer- 
ence guide. Over 50,000 cross references. Free 
update service through 1979. Domestic postage 
$3.50. No foreign orders. 



Not a Cheap Clock Kit $14.95 

Includes everything except case. 2-PC boards. 
6-. 50" LED Displays. 5314 clock chip, trans- 
former, all components and full instructions. 
Orange displays also avail. Same kit w/,80" 
displays. Red only. $21.95. Case $11.75 



NiCad Battery Fixer/Charger Kit 

Opens shorted cells that won't hold a charge 
and then charges them up, all in one kit w/full 
parts and instructions. $7.25 



S-100 Computer Boards 

8K Static RAM Kit S135.00 

16K Static RAM Kit 265.00 

24K Static RAM Kit 423.00 

32K Static RAM Kit 475.00 

16K Dynamic RAM Kit 199.00 

32K Dynamic RAM Kit 310.00 

64K Dynamic RAM Kit 470.00 

8K/16KEprom Kit (less PROMS) $89.00 

Video Interface Kit $129.00 
Motherboard $39. Extender Board $8.99 



Video Modulator Kit $8.95 

Convert your TV set into a high quality monitor 
without affecting normal usage. Complete kit 
with full instructions. 



Digital Temp. Meter Kit $34.00 

Indoor and outdoor. Switches back and forth. 
Beautiful. 50" LED readouts. Nothing like it 
available. Needs no additional parts for com- 
plete, full operation. Will measure -100° to 
+ 200°F, tenths of a degree, air or liquid. 
Beautiful woodgrain case w/bezel $11.75 



FREE: Send for your copy of our NEW 1979 
QUEST CATALOG. Include 28« stamp. 



Circle 177 on inquiry card. 



BYTE February 1980 227 



Circle 178 on inquiry card. 



PRINTED CIRCUIT BOARD 



4" x6" DOUBLE SIDED EPOXY 

BOARD 1/16" thick 

$.60 ea 5/S2.60 

EPOXY glass vector hoard 

1/16 " thick with 1/10" spacing S1.95 

VERIPAX PC BOARD $12.95 

Oiif new Prototyping board Is a hi density 
A'/i x 6'/;" single sided 1/16" G-10 board. It will 
Hold 40, 24, 16 [34 units), 14 * B pin IC's. 
There are three busses, *5V, ground and a. 
' ' if a TO-220 reg- 



156" 



i 22 I 



7WATTLD65LASERDIODEIR $a95 



TTL REED RELAY - 5PST 5V 20ma S1.00 



DAC-08BC - 8 bit DAC - $9.95 
8" DISKETTES - HARD SECTOR 
Si. 75, 10/S 16.00 



!5 watt Infra Red Pulse I SG 2006 eqjliv, ) 

.aser Diode <Spec sheet included! $24.35 

MINIATURE MULTI-TURN TRIM POTS 
100, 2K, 5K, 10K, 20K, IMeg, $.75 
each 3/$2.O0 

2N 3820 P FET $45 

2N 5457 N FET $ 45 

2N2646 UJT $ .45 

ER 900 TRIGGER DIODES 4 SI 00 

?N 6028 PROG UJT S §5 

FP 100 PHOTO TRANS S .50 

RED, YELLOW, GREEN 

LARGE LED's. 2" 6/$1 .00 

RED/GREEN BIPOLAR LED's. 2" . ..95 

TIL-118 0PTO-ISOLATOR $.75 

MCT-6 OPTO ISOLATOR $ .80 

1 WATT ZENERS; 3.3, 4.7, 5.1, 5.6, 9.1, 
1 0, 1 2, 1 5, 1 8, or 22V 6/$ 1 .00 



Silicon Power Rectifiers 



TRANSISTOR SPECIALS 

2N6233-NPN SWITCHING POWER . SI. 95 
MRF-8004 a CB RF Transistor NPN . $ .75 

2N3772 NPN Si TO-3 $1.00 

2N4908PNP Si TO-3 $1.00 

2N5086 PN P Si TO-92 4 $ 1 .00 

2N3137 NPN Si RF $ .55 

2N3919 NPN Si TO-3 RF $1.50 

2N1420 NPN Si TO-5 3/$ 1.00 

2N3767 NPN Si TO-66 $ .70 

2N2222 NPN Si TO-18 5 $1.00 

2N3055 NPN Si TO-3 $ .60 

2N3904 NPN Si TO-92 6/$ 1.00 

2N3906PNP Si TO-92 G/Sl.00 

2N5296 NPN Si TO-220 $ .50 

2N6109 PNP Si TO-220 $ .55 

2N3638PNPSiTO-5 5/S1.00 

MPSA 13 NPN Si 4/$ 1.00 

TTL IC SERIES 



■ ZEHH M 



1.30 



1 90 



DIP SOCKETS 



^IN .25 



SANKEN AUDIO POWER AMPS 

Si 1010 G 10 WATTS S 6.75 

Si 1020 G 20 WATTS $12.95 

Si 1 050 G 50 WATTS . . . S25.90 



TANTULUM CAPACITORS 



CRYSTALS S3.45 oa. 
2.000 MHz 6.144 MHi 
4.000 MHz 8.000 MHz 
3.57 MHz 10.000 MHz 
5.000 MHz 20.000 MHz 
6.000 MHz 



RIBBON CABLE 
LAT (COLOR CODE 
M0WIRE 



UNIVERSAL 4Kx8 MEMORY BOARD KIT 
S69.95 

322102-1 fully buffered. 16 address linos, or 
board decoding for any 4 of 64 pages, standaro 
44 pin buss, may be used with F-8 & KIM 



SILICON SOLAR CELLS 
I" diameter .4V at 1 AMP $10.00 



LED READOUTS 



FCS 8024 4 dj 
C.C. 8" display 
FND 503 C.C 
FND 510 C.A. 
DL 704 .3" C.C. 



DL-707C.A. .3" 

5.95 DL 747 C.A 6" 

85 HP3400 .8" CA 

HP3405 .8" CC 



10 50 16.50 



12.50 20.00 



RS232 DB25Pmaie $2.95 

CONNECTORS DB 25S femata $3.50 

HOODS $1.50 



323K - 5V 3A . .$ 5.75 
309K ... . .S 1.60 

723 S .50 

320T- 

5, 12, or 15 V 



REGULATORS 

340K - 12, 15 

or 24 V. . . .S 1.50 
340T - 5, 6,8, 12 

15, IBor 24VS 1.30 
79MG S1.35 



3/Sl.OO 

$.40 ea. 

MM5387AA . . . CLOCK CHIPS - ■ S5.95 

M7001 57.50 

MM531 1 _S3 1 7S_ 

NO. 30 WIRE WRAP WIRE SINGLE 

S TRAND 100' $1.40 

CO MINIATURE TOGGLE SWITCt 
MTA 106 SPOT S 1.05 

MTA 206 DPDT ... S 1 70 

MTA 206 P. DPDT CENTER OFF 
MSD 206 P- DPDT CENTER OFF 
LEVER SWITCH. . . . , $ 1.85 



.22UF 35V5/S1.00 
.47UF 35V5/S1.00 
.68UF 35VS/S1.00 
1UF 35V 5/S1.00 
2.2UF 20V 5/S1.00 
3.3UF 20V 4/41.00 
4.7UF 15V 5/S1.00 



MlS Series 



6.8UF 35V 4/51.00 

10UF 10V S .25 

22UF 25V $ .40 

15UF 35V 3/S1.00 

30UF 6V 5/S1.00 

100UF 15V $ .70 

' 160UF 15V $ .35 
68 UF 1 



74LS03 - 
74LS04 - 
74LS0S - 
74LS08 - 



74LS28 - 
74LS30 — 
74LS32 - 
74LS37 — 
74LS38 - 
74LS40 - 
74LS42 — 
74LSS1 - 
74LS54 
74LS73 - 
74L574 — 
74LS75 - 
74L576 - 



74L.593 - 
74LS1Q7 - 
74LS100 - 



74LS114 
74LS125 
74LS126 



74L5: 
74 LG 
74LS; 



74LG221 
74LS107 
74LB240 



5 74LS251 — 

5 74LS257 - 

5 74LS25B — 

05 74LS253 — 

>9 74LS265 - 

E 74LS2C6 — 

5 74LS279 — 

'0 74L5290 — 

'0 74LG293 - 

° 74LS29S- 



74LS367 - 
74LS36B - 
74LS273 - 



9 74LS390 — 1.95 



LINEAR CIRCUITS 

LM201 — .75 
LM301/748 - .25 
LM307 - .30 
LM308 - .75 
LM311 — .75 
LM318 — 1.20 
LM324 — .95 
LM339 - 1.10 
LM358 - .70 
LM370 — 1.15 
LM377 — 1.60 
LM380 — .95 
LM382 - 1.25 
LM386 - .80 
LM387 — 1.25 
LM1800 — 2.20 
LM1B0B — 1.75 
CA3080 — .95 
LM537 — 2.50 
LM553 - 2.50 
LM555 — .49 
LM5G6 — .85 
560 — 2.00 

565 - .95 

566 - ' 

567 - 

702 — 

703 - 

709 — 

710 — 



74 7 



.50 



.30 



- 2.50 



-M1310 - 
1456 — .9b 
1458- .50 
3900 — .85 
8038CC - 3.90 
791 - 1.95 
4136 -.95 




UP TO 25% OFF^ 

YOUR OWN TRS-80 SYSTEM AT TREMENDOUS SAVINGS 

DISK DRIVES IN STOCK/ 



OTRS-80 Complete System 

Includes: CPU/ Keyboard, Power Supply, 
Video Monitor, Cassette Recorder, Manual, 
and Game Cassette. 

Q Line Printer 
©Mini Disk System 
QC- 10 Cassettes 
©Verbatim Diskettes 






REG. 


OUR 


ITEM 


PRICE 


PRICE 


Level II— 4k 


$619.00 


$575.70 


Level II— 16k 


$849.00 


$789.60 


Expansion Interface 


$299.00 


$278.00 


Mini Disk Drivo 


$ 495 00 


$ 38500 


Centronics 779 Printer 


$1599.00 


$1175.00 


Centronics 101 Printer 


$1595 00 


$1400 00 


Anadex DP-8000 Printer 


$1295 00 


$ 99500 


Memory Kit-(16K) FREE installat 


ON $ 149.00 


$ 98.00 


Verbatim Diskettes ea 


$ 5 95 


$ 4 95 


3 


$ 17 89 


$ 1200 


10 


$ 59.00 


$ 37.50 


C-10 Cassettes 5 


$ 4 95 


S 450 


25 


$ 2475 


S 1875 


Paper (9V 2 x 1 1 lanfold. 






3500 sheets) 

C A 1 


$ 35.00 


$ 29.95 


oALl 




Centronics 730 


$850.00 


Same as Line Printer II 


TRS— 80 MODEL II 


$3626.00 


• 64KRAM 






• '/2 MEG DISK 






VR Data's 1 st Drive 




$899.00 


ADDITIONAL DISK DRIVE ( 


1ST) 


$1069.50 


ADDITIONAL DISK DRIVE (2ND + 3RD) 


$ 540.00 



\^@adau 

777 Henderson Boulevard N-6 
Folcroft Industrial Park 
Folcroft PA 19032 
(215) 461-5300 

TOLL FREE 

1-(800) 345-8102 Orders on 

FOREIGN and DOMESTIC DISTRIBUTORSHIPS AVAILABLE 



MINI DISK DRIVES NOW $385 

Over $100 less than Radio Shack's ! 




There are new developments every day — 
write or call for the latest information. 



ly! 



If 1 I I I I I I 1 1 1 1 1 1 T I I I I I I I I T 1 T T» n ' 1 1 1 



228 BYTE February 1980 



Circle 179 on inquiry card. 



Moonshadow Text Formatter for 
UCSD Pascal™ Systems 

The UCSD PascafM system contains a 
screen-oriented text editor which is convenient, 
but which is not suited to word processing. It can- 
not underline, paginate automatically, or perform 
other essential text-processing functions. The 
Moonshadow Text Formatter (MTF) from Merri- 
mack Systems solves this problem. 

With the Moonshadow Text Formatter, docu- 
ments produced with the screen editor are post- 
processed to provide these missing functions. It 
takes standard Pascal text files, operates on 
them, and sends fully formatted text output to the 
console display, a printer, or a disk file. 

Moonshadow Text Formatter provides, in addi- 
tion to a full range of formatting functions, ad- 
vanced features including the comDination of 
files into one document, variables in text (for form 
letters), and output character translation. 

The Moonshadow Text Formatter is written in 
UCSD PascalTM, and is available for North Star 
Apple II, LSI-II. and 8080/Z80 systems with IBM 
Format 8" floppy disks. 

All this for S99.00 from 

Merrimack Systems 

POB 5218 

Redwood City, CA 94063 

(415)365-6281 

California residents should include 6% sales tax. 
Also available: North Star Pascal personaliza- 
tion for SOL/SOLOS — just transfer three files 
and you're up with Pascal. $25.00 



New from 
Vantage Data Products 

550 West 200 South 
Suite8 

■Provo.Utah 84601 
(801)377-6687 




■ $ ■'-; i t .,% 



Communications/Control CPU Card 

« CPU-Z-801KRAM 

16 bit interval timerand interrupt 
EPROM* 2708 standard (2716 optional) 

•Serial Communications-RS-232 interface, 

UART Complete MODEM capability, 
programmable baud rates, etc. 

•Parallel I/O - 16 bits in (TTL), 16 bits Out (TTL) 

•Power - on and external reset 
'EPROM not included 

$195 assembled, tested, with warranty and 
documentation 

Immediate delivery from stock! 

All orders shipped prepaid 

MC, VISA, phone orders welcome 

Utah residents add 4Wsales tax 



STATISTICAL DATA 

DATABANK programs contain 10 
years of monthly statistical data on 
ten related subjects. Information is 
the most current available. Each 
cassette is date stamped. Includes 
graphs, tables, trends, comparisons, 
update routine, and external input. 

Programs available for TRS-80 LS, 16K 

* General Economy 

* Manufacturing & Trade 

* Industrial Production 

* Money & Credit 

* Money Rates & Yields 

* Commodity Spot Prices 

* Mortgage Terms & Yields 

* Foreign Exchange Rates 

* Energy Production 

* Petroleum Production 

$29.95 each 3 for $84.95 

Cassette storage album included with 
order for six or more programs. 

jllfc DATABANK POB 9283 
HIP Ft Lauderdale, FL 33310 



Circle 180 on inquiry card. 



Circle 181 on inquiry card. 



Circle 182 on inquiry card. 




16K STATIC MEMORY (RAM) 

250 nsec Access Time, Assembled, 
tested, and Guaranteed. $300.00 

Fully Static - TMS 4044 

S-100 Bus- Buffered lines, Dip Sw address in 

2, 8K blocks4K incr., Write Protect, Phantom 

disable. Battery backup, fully Socketed. 

Bank Select - Port 40 H (Cromemco Software 

Comp.J, 80H or COH. 

Guarantee - One full year. To order, call for 

Visa, M.C., or C.O.D. ($4 fee.) Personal check 

o.k. M.O. speeds shipping. Stock to 72 hour 

delivery. Illinois residents add 5'/4% tax. 

S. C. DIGITAL 

P.O. Box 906, Aurora, IL 60507 
Phone: (312) 897-7749 



DISCOUNT PRICES 

NORTH STAR 

APPLE II 

POLYMORPHIC 

INTERACT 

HAZELTINE 

SOROC 

CENTRONICS 

MICROTEK 

INTERTUBE 

& Others 

Call for Prices 
(301)694-8884 

FREDERICK COMPUTER 
PRODUCTS 

Municipal Airport 
Frederick, MD. 21701 



SUPPLIES 




• FLOPPY DISKS, MINI OR 
STANDARD MEMOREX OR 3M 

■ 3M DATA CARTRIDGES 
DC3D0A, DC100A 

■ 3M DIGITAL CASSETTES 

• 3M OR MEMOREX AUDIO 
CASSETTES. C-60 

■ 3M DISK CARTRIDGES 

WE OFFER: 
•COMPETITIVE PRICING 
•IMMEDIATE DELIVERIES 

(Any Quantity) 
• UNCONDITIONAL GUARANTEE 

BETA BUSINESS SYSTEMS 

8369 VICKERSST.. #G 
^^» SAN DIEGO, CA 921 1 
[7)41 565-1505 



Circle 183 on inquiry card. 



Circle 184 on inquiry card. 



Circle 185 on inquiry card. 



H9 OWNERS! 



Now you too can have graphic capa- 
bilities similar to those of the TRS-80 
with GRAFIX. No modification to ex- 
isting circuit boards is required. 
GRAFIX simply plugs into existing IC 
sockets. 

Comes with complete instructions. 
Full 6 month warranty. 

Kit $59.95 

Assembled and tested $69.95 

Northwest Computer 

Services, Inc. 
8503 N.E. 30th Avenue 
Vancouver, WA 98665 



Texas Instrument 99-4 Computer 


$ 990. 


TI 810 Printer 


$1590. 


Centronic Printers: 




730-1 Parallel 


$ 799. 


730-2 Serial 


$ 859. 


779-1 Friction Feed 


$ 959. 


779-2 Tractor Feed 


$ 999. 


Comprint 912 Par 


$ 475. 


912 Ser 


549. 


Anadex with Par & Serial Interlace 


* 799. 


Commodore Business Machines: 




PET 2001-BK Computer 


$ S95. 


PET2001-16K 


$ 895. 


PET2001-32K 


$1090. 


PET 2022 Trac. Fed Printer 


$ 899. 


PET 2023 Frig. Fed 


$799. 


$75. Free Soitware with PET Machines 


lntertec Superbrain 




North Star Computer and Ace. 




Save $ Save $ 




Display Terminals: 




Intertube II 


$ 775. 


Hazeltine 1400 


$ 690. 


1410 


$ 785. 


1500 


$ 990. 


Immediate Delivery from Stock. 




Multi-Business Computer System 




28 Marlborough Street 




Portland, Conn. 06480 




(203) 342-2747 






SEARCHING THROUGH 
YOUR ENTIRE 

NORTH STAR 

BASIC PROGRAM LISTINGS. 



WITH OUR NEW "SCAN" COMMAND YOU CAN 
INSTANTLY DISPLAY OR PRINT - 



JNES THAT CONTAIN A SELECTED VARIABLE. 



• ALL REFERENCES TO ANY LINE NUMBER 

• ALL OCCURRENCES OF ANY CHARACTER. NUMBER, 
LINE NUMBER. GROUP OF CHARACTERS OR ANYTHING 
THAT IS CONTAINED IN ANY BASIC LINE. 

This is not one or those ■'funny programs written in BASIC." It is » 
machine language addition to BASIC thai resides completely within 
NORTH STAR BASIC. It will not eltecl normal BASIC qi DOS. Il is 
sell loading and can be loadec separately lo operate with BASIC 
of saved along with BASIC as a copy ol BASIC wilh the "Scan" com- 
mand. Does nol change memory available to BASIC Easy lo under 



• Available for version 6 as well as 14 digit basic 

• Slate your version when ordering 

• Dealer inquiries invited 

PHONE ORDERS ACCEPTED 

ORDER TODAY 
USE YOUH VISA OR MASTERCHARGE C 



ONLY $275° °-°* 



H 



ELECTRONIC TECHNICIANS 
SOFTWARE SERVICES 
1072 CASITAS PASS RD. 
CARPINTERIA. CA 93013 

805-684-2541 



Circle 186 on inquiry card. 



Circle 188 on inquiry card. 



Circle 189 on inquiry card. 



!M:l:VA7M:l 



ELECTRONICS 

America's Largest Mail-Order Computer Store 



74L$ 



1.25 
.39 



| Order by Cat No. 

NO. PRICE 

74LS00 .28 

74LS01 .19 

74LS02 .29 

74LS03 .19 

74LS04 .89 

74LS05 .35 

74LS08 .29 

74L$09 .25 

74L$10 .29 

74L$11 .59 

74LS12 

74LS13 

74LS14 

74LS15 

74LS20 

74LS21 

74LS22 

74LS26 

74LS27 

74LS28 

74LS30 

74L532 

74LS33 

74LS37 

74LS38 

74L$40 

74LS42 

74LS47 

74LS48 

741551 

74LS54 

74LS55 

74LS73 

74LS74 

74LS75 

74LS76 

74LS83 

74LS85 

74L$B<> 

74L590 

74LS92 

74LS93 

74LS95 

741596 

74LS107 



999 and type 
NO. PRICE 

74 LSI 57 
74 LSI 58 
74 LSI 60 
74LS161 
74 LSI 62 
74 LSI 63 
74 LSI 64 
74 LSI 65 
74LS168 
74 LSI 69 
74 LSI 70 
74LS173 
74LS174 
74LS175 
74LS181 
74 LSI 90 
74 LSI 91 
74LS192 
74LS193 
74LS194 
74LS195 
74LS196 
74 LSI 97 
74LS221 
74LS240 
74LS241 
74LS242 
74LS243 
74LS244 
74LS247 
74 L$ 24(1 
74LS251 
74LS253 
74LS257 
74LS25H 
74LS259 
74LS260 
74LS261 
74LS266 
74LS273 
74LS275 
74LS279 
74LS283 
74LS293 
74LS295 



1.45 



1.10 



1.25 



2.25 
1.10 
1.10 
1.10 
1.10 
1.10 
1.10 
.89 
1.65 
1.25 
4.50 
2.40 
1.50 
2.50 
2.60 
1.10 
1.10 
1.99 



1.99 



1.75 



1.95 
.99 



TTL 

Order by Cat No. 999 and type 



7402 


.18 


74120 


7403 


.10 


74121 


7404 


.11 


74122 


7405 


.19 


74123 


7406 


.19 


74125 


7407 


.19 


74126 


7408 


.19 


74128 


7409 


.19 


74132 


7410 


.19 


74136 


7411 


.25 


74139 


741 2 


.25 


74141 


7413 


.35 


74143 


7414 


.60 


74145 


7416 


.19 


74148 


7417 


.25 


74150 


7420 


.19 


74151 


7422 


.79 


74153 


7423 


.22 


74154 


7425 


.25 


74155 


7426 


.35 


74156 


7430 


,19 


74157 


7432 


.25 


74160 


7437 


.25 


74161 


7430 


.25 


74162 



74 LSI 09 
74LS112 
74LS113 
74 LSI 14 
74 LSI 22 
74LS123 
74LS124 
74 LSI 25 
74 LSI 26 
74LS132 
74 LSI 38 
74 LSI 39 
74LS145 
74 LSI 51 
74LS153 
74 LSI 54 
74LS155 
74LS156 



.79 
1.79 



74LS298 

74LS365 

74LS366 

74LS367 

74LS368 

74LS373 

741.5374 

74LS377 

74LS378 

74LS386 

74LS393 

74LS395 

74LS399 2.95 

74LS424 

74LS668 

74LS670 

81 LS 96 

OILS 97 



3.05 
1.95 
3.90 
1.25 



1.45 



1.25 
2.49 
1.45 
1.55 



7440 
7441 
7442 
7443 



7453 
7454 
7460 
7470 
7472 
7473 
7474 
7475 



7480 
7481 

7482 
7483 
74B5 
74B6 
7489 
7490 
7491 
7492 
7493 



BSE 

Wmjm 



74176 
74177 
74179 
74780 
74181 
74182 
74184 
74185 
74190 
74191 
74192 
74193 



74197 
74198 
74199 
74221 
74251 
74273 
7427B 
74279 
74298 
74365 
74366 
74376 
74160 



MICROPROCESSORS] 

Order by Cat No. 999 and type \ 

TYPE NO. PRICE 



Z80 A 


12.75 


1802 


16,50 


6502 


14.50 


6800 


6.50 


8035 


11.75 


8080 A 


6.60 


8085 


15.95 


TMS 9900 


49.00 



CALL TOLL FREE: 

(800) 423-5387 USA 

IN CALIF: 

(800) 382-3651 



r* 6 \ 

bbb: 



i 


LUUAL « V 

(213) 88 


MICROPROCESSOR 




SUPPORTS 




Order by Cat No. 999 and type 


NO. 


PRICE 


NO. 


PRICE 


8212 


2.95 


280A CTC 


13.95 


8214 


4.95 


Z80A 5I0 


55.00 


8216 


2.60 






8224 


3.95 


6810 


5.95 


8226 


3.95 


6820J6520 


6.96 


8228 


5.95 


6821 


6.95 


8238 


6.75 


6828 


1 1 .95 


8251 


6.95 


6850 


9.95 


8253 


11.50 


6852 


6.50 


8255 


7.95 


6860 


9.95 


8257 


15.95 






8259 


18.95 


1822 


18.95 


8279 


9.50 


1852 


7.50 


8271 


17.50 


1854 


13.95 


Z8OA-PI0 13.95 


1861 


15.95 



RAMS/EPROMS 

Order by Cat No. 999 and type 



TYPE NO. 


PRICE 


1101 


.79 


2101-250 


1.95 


2101-450 


1.25 


21L02-650 


.79 


2IL02-450 


1.10 


21L02-250 


1.25 


2111-400 


2.95 


2114-300 


7.25 


2114-200 


9.75 


4027P-2 


3.90 


TMS 4045-450 


6.50 


TMS 4045-300 


7.25 


41 16-300 


11.65 


4116-250 


12.75 


4116-200 


13.75 


4116-150 


14.90 


9050 CDC 


4.50 


91 L02-450 


.79 


1702 A 


4.25 


TMS 2532 


86.00 


2708 


9.15 


2716 


27.00 



16K MEMORY 


ADD-ON 


S75 


2 for S140 


For TRS-S0, Apple. Exidy 


Installs 


n minutes, no special 


tools required. Complete with 


detailed 


instructions. Wt 4 oz. 


Col No. 


Description 


1156 


For TRS-H0 keyboard 


1156A 


TR5-80 without buf- 




fered cable 


11568 


TRS-80 with buffered 




cable 


1156C 


For Apple 


11.i6D 


For Exidy Sorcerer j 



HOW IO ORDER: 
Pay by check. Mulercharge, 
Visa, or COD. Cliar K L- orders 
please include eipiralion dale. 
Foreign pay in U.S. fundi. Order 
by phone or mail, 01 at OUt retail. 
MINIMUM ORDER Sin. please 
Include phone number and mag? 
a/inelisiue you are ordering 
(mm. Prices valid Ihrn l.isl da\ ol 
cmer date. SHIPPING: USA:: 
add $2.00 for the first J lbs. For 
ground add !!5< lot adill'l lb. for 
air add Tic lor ailrit'l lb. FOR- 
EIGN: surface: add S.i.tMi tor lirsl 
I tbs. r.tK per ailill'l lb. Air: add 
SM.00. for lirsl 2 lbs. $i lor each 
addl'l lb. COFJs SI addl'l. Guar- 
anteed satisfaction lor 121) days 
■ b.ick! Nol rc- 



s.bl,. 



typoi 



. Snme items subject In 
prior sale. We reserve (be right 
lo limit quantities, 
SEND FOR FREE CATALOG 
FEATURING: 
Computers .inrl accessories, disk 
drives, printers, integrated cit- 
icomlucli.rs. 






Thev 



19511 Business Center Dr. Dept. B2 Northridge, Ca. 91324 




BUILD YOUR OWN LOW COST 
MICRO-COMPUTER 

POWER SUPPLIES 

FOR S-100 BUS, FLOPPY DISCS, ETC. 




POWER TRANSFORMERS (with mounting brackets) 



ITEM 
NO. 



USED IN 
KIT NO. 



PRI. WINDING 
TAPS 



SECONDARY WINDING OUTPUTS 
2x8 Vac 2x14 Vac 2x24 Vac 



SIZE 
W x D x H 



UNIT 
PRICE 



T1 
T 2 
T 3 

T 4 



0V, 110V, 120V 
0V, 110V, 120V 
0V, 110V, 120V 
0V, 110V, 120V 



2x7.5A 

2x12.5A 

2x9A 

2x4A 



2x2. 5A 
2x3.5A 
2x2.5A 



2x2.5A 
2x3A 



3%"x3 5 /8"x3 1 /8" 
3%"x4 3 /8"x3Va" 
3%"x4 3 /8"x3Vs" 
3%"x3 5 /e"x3V8" 



21.95 
27.95 
29.95 
21.95 



POWER SUPPLY KITS (open frame with base plate, 3 hrs. assy, time) 

ITEM USED FOR @+8Vdc @-8 Vdc @ + 16 Vdc (5j-16Vdc (S + 28Vdc 



SIZEWxDxH UNIT PRICE 



KIT1 15 CARDS SOURCE 15A 

KIT 2 SYSTEM SOURCE 25A 

KIT 3 DISC SYSTEM 15A 

KIT 4 DISC SOURCE 8A 



1A 
1A 



2.5A 
3A 
2A 



2.5A 
3A 
2A 



4A 
5A 



12"x6"x4%" 
12"x6"x4%" 
14"x6"x4%" 
10"x6"x4 7 /b" 



51.95 
58.95 
66.95 
49.95 



EACH KIT INCLUDES: TRANSFORMER, CAPACITORS, RESIS., BRIDGE RECTIFIERS, FUSE & HOLDER, TERMINAL BLOCK BASE 
PLATE, MOUNTING PARTS AND INSTRUCTIONS. 

DISC DRIVE POWER SUPPLY "R3" assy. & tested, open frame, size: 9" (w> x 5" (D) x 5" (H) 59.95 

SPECS: +5V@5A REGULATED, -5V@ 1AREG., +24V@ 5A REG., SHORTS PROTECT. 

IDEAL FOR 2 SHUGART 801/851 OR SIEMANS FDD 1 00-8/200-8 DISK DRIVES & ROCKWELL AIM-65. 

SHIPPING FOR EACH TRANSFORMER: S4.75. FOR EACH POWER SUPPLY: S5.00 IN CALIF. S7.00 IN OTHER STATES. CALIF. RESIDENTS ADO 6% SALES TAX. OEM WELCOME. 



MAILORDER: 

P.O. BOX 4296 

TORRANCE, CA 90510 



SUNNY INTERNATIONAL 

(TRANSFORMERS MANUFACTURER) 
Telephone: (213) 633-8327 



STORE: 

7245 E. ALONDRA BLVD. 

PARAMOUNT, CA 90723 

STORE HOURS: 9 AM-6 PM 




230 BYTE February 1980 



Circle 190 on inquiry card. 



DIGITAL RESEARCH COMPUTERS 

(214) 494-1505 



16K EPROM CARD-S 100 BUSS 





FIRST TIME OFFERED! 
BLANK PC BOARD - $28 

USES 2708s! 

Thousands of personal and business systems around the world 
use this board with complete satisfaction. Puts 16K of software 
on line at ALL TIMES! Kit features a top quality soldermasked and 
silk-screened PC board and first run parts and sockets. Any 
number of EPROM locations may be disabled to avoid any 
memory conflicts. Fully buffered and has WAIT STATE 
capabilities. 



OUR 450 NS 2708'S 
ARE $8.95 EA. WITH 
PURCHASE OF KIT 



ASSEMBLED 

AND FULLY TESTED 

ADD $25 



8K LOW POWER RAM KIT-S 100 BUSS 

SALE 



■■■ ■ -: ■ ■ ■ ■ . ■ ' .:■ : 







$ 1 1 9 5 £ 



21L02 
(450 NS RAMS!) 

Thousands of computer systems rely on this rugged, work horse, 
RAM board. Designed for error-free, NO HASSLE, systems use. 

Blank PC Board w/Documentation 

$29.95 

Low Profile Socket Set. ..13.50 



ASSEMBLED AND FULLY 
BURNED IN ADD $30 



ALL ASSEMBLED BOARDS 
ARE TESTED AT 4MHZ. 



Support IC's (TTL & Regulators) 

$9.75 
Bypass CAP'S (Disc & Tantalums) 

$4.50 



16K STATIC RAM KIT-S 100 BUSS 



16K STATIC RAM SS-50 BUSS 



PRICE CUT! 



nx%r^3sssr 



$ 259 



KIT 




.^iiiiiiiiiiiLiiiM^ 



PRICE CUT! 





flHHUB 

1 . Addressable as four separate 4K Blocks. 

2. ON BOARD BANK SELECT circuitry. (Cro- 
memco Standard!}. Allows up to 512K on line! 

3. Uses 2114 (450NS) 4K Static Rams, 
4.- ON BOARD SELECTABLE WAIT STATES. 

5. Double sided PC Board, with solder mask and 
silk screened layout. Gold plated contact fingers. 

6. All address and data lines fully buffered. 

7. Kit includes ALL parts and sockets. 

8. PHANTOM is jumpered to PIN 67. 

9. LOW POWER: under 1.5 amps TYPICAL from 
the +8 Volt Buss. 

10. Blank PC Board can be populated as any 
multiple of 4K. 



« ;■ 



BLANK PC BOARD W/DATA-$33 
LOW PROFILE SOCKET SET-$12 

SUPPORT IC'S & CAPS-$19.95 
ASSEMBLED & TESTED-ADD $30 



FULLY STATIC 

AT DYNAMIC 

PRICES 



leBiiiiiEiiiiiii 
iiiiniiiiiiiiii 



: 



FOR SWTPC 
6800 BUSS! 



OUR #1 SELLING 
RAM BOARD! 



KIT FEATURES: 

1. Addressable on 16K Boundaries 

2 Uses 2114 Static Ram 

3. Runs at Full Speed 

4. Double sided PC Board Solder mask 
and silk screened layout. Gold fingers. 

5. All Parts and Sockets included 

6. Low Power: Under 1.5 Amps Typical 

BLANK PC BOARD— $26 COMPLETE SOCKET SET— $12 
SUPPORT IC'S AND CAPS— $19.95 



ASSEMBLED AND 
TESTED - $30 



PROC TECH. QUITS THE MICROPROCESSOR BUSINESS! 

FACTORY CLOSE OUT - SPECIAL PURCHASE! 

#16KRA 

16K S-100 Dynamic Ram Board 
$149.95 

We purchased the remaining inventory of PT's popular 16K Ram 
Board when they recently closed their plant. Don't miss the boat! 
These are brand new, fully tested, ASSEMBLED and ready to go. 
All are sold with our standard 90 day limited warranty!! 
Orig. $429 each! 72 Page Full Manual, Included Free! 



Perfect for 
OEM's 



S-100 Z80 CPU CARD 



*159 



95 



WIRED! 
NOT A KIT! 



4 MHZ 




Z-80 PROGRAMMING MANUAL 

By MOSTEK, or ZILOG. The most detailed explanation ever on the 
working of the Z-80 CPU CHIPS. At least one full page on each of the 158 
Z-80 instructions. A must reference manual for any user of the Z-80. 300 
pages. $12.95 



ASSEMBLED AND TESTED! READY TO USE! Over 3 years of design 
efforts were required to produce a TRUE S-100 Z80 CPU at a genuinely 
bargain price! BRAND NEW! 

FEATURES: 

+ 2 or 4 MHZ Operation * Generates MWRITE, so no front panel required. 
• Jump on reset capability. ■* 8080 Signals emulated tor S-100 comparability 
* Top Quality PCB. Silk Screened. Solder Masked Gold Plated Contact Fingers 



c , LOW POWER - 250NS 8 FOR 

sM- fc ' 2114 RAM SALE! $55 

4K STATIC RAM'S. MAJOR BRAND, NEW PARTS. 
These are the most sought after 2114's, LOW POWER and 250NS FAST. 
SPECIAL SALE: $7 50 ea. or 8 For $55 



NEW! G.I. COMPUTER SOUND CHIP 

AY3-8910. As featured in July, 1979 BYTE! A fantastically powerful Sound 
& Music Generator. Perfect for use with any 8 Bit Microprocessor. 
Contains: 3 Tone Channels, Noise Generator, 3 Channels of Amplitude 
Control, 16 Bit Envelope Period Control, 2-8 But Parallel /O. 3 D to A 
Converters, plus much more! All in one 40 Pin DIP. Super easy to interface 
to the S-100 or other busses. 
SPECIAL OFFER: $14.95 each Add $3 for 64 page Date. Manual. 



Digital Research Computers 

^ (OF TEXAS) ' 

P.O. BOX 401565 • GARLAND, TEXAS 75040 • (214) 494-1505 



TERMS: Add $1.00 postage, we pay balance. Orders under $15 add 75C 
handling. No C.O.D. We accept Visa and MasterCharge. Tex Res. add 5% 
Tax. Foreign orders (except Canada) add 20% P & H. 90 Day Money Back 
Guarantee on all items. 



NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA, THE SUPPLIERS OF CPM SOFTWARE. 

Circle 191 on inquiry card. 



BYTE February 1980 231 



g£ 




/MICRO 

BUSINESS WORLD 

Immediate response to your orders (verbal or written). Phone (213) 371 -1 660 





Apple II 
personal 
computer. 



16K 
Regular 
or Plus 

$ CALL 



$ CALL 



Disk II with controller 
Disk II without controller $ CALL 
PASCAL Language Card $ CALL 
CALL for our lowest prices ever. 
We carry all peripherals and 
interface boards for the APPLE. 
European versions available. 



DYSAN DISKETTES 

THE CADILLAC OF THE 

FLOPPY DISKS 
AT LOW LOW PRICES 

8" (BOX OF 10) 

3740/1 sgl side/ 

sgl density 4.00 ea 
3740/1 D sgl side/ 

dbl density 6.50 ea 
5" (BOX OF 5 ) 
104/1 soft sector 4.00 ea 
107/1 10 sectors 4.00 ea 

105/1 16 sectors 4.00 ea 

For each 2 boxes ol 8" or 4 

boxes ol 5" you gel one 

plastic storage case, but 

hurry — supply is limited 



EPSON (A SEIKO COMPANY) 
TX-80 Printer with 64 
graphics characters 
7x5 dot matrix (7x6 in 
graphics) Double 
width characters 




ATARI 800 Compute System 

Packed with: Computer Console. 
Basic Language Card. Education 
System Master Cartridge, Cassette 
Recorder. TV Modulator. 8K Memory 
(expandable to 48K). Power Supply 
& all Books and Manuals $ CALL 

ATARI 400gS}o c S uter 

Packed with: Computer Console, 
Basic Language Cartridge. Power 
Supply, TV Modulator, and all 

Books and Manuals $ CALL 
ATARI Program Recorder $ CALL 

ATARI Software. Roms. Cassettes* CALL 
ATARI Expansion Memory: $ CALL 

8K Module or 16K Module $ CALL 
CALL for our lowest prices ever. 



Plastic Floppy Disk Holder 

(up to 10) 8" $3.95 
(up to 10) 5" $3.25 

16K RAM setof8 4116's 

200 ns or better $65.00 



Tractor Feed Model $695.00 

Friction Feed Model $595.00 

TRS80 Interfaces Cable $50.00 

Pet Interface & Cable $80.00 

APPLE Interfaces Cable $80.00 

RS232 Interfaces Cable $80.00 



Prices subject to change without notice. 
VISA and MASTER CHARGE WELCOME (Add 3%) 
Allow 2 weeks for cashiers check to clear. 4 weeks 
for personal checks. Add 2% for shipping and 
handling. Calif, residents add 6% sales tax. 
U.S. and International dealer inquiries invited. 



ZENITH DATA SYSTEMS: 

Smart Video Terminal 




Z-19 has a Z80 Microprocessor. 
Numeric Keypad and 8 function 
key $895.00 





Z-89 Computer System: 

includes: Z19 Display, a built in 
5 V Floppy Disk, 2 serial ports, 
and 16K of memory. 2295.00 
48K Memory version 2595.00 

/VIICRO 

BUSINESS WORLD 

15818 Hawthorne Boulevard 
Lawndale, California 90260 
(213)371-1660 




AIM 65 

AIM 65 is fully assembled, tested and warranted. With the addition of a low cost, readily available power 
supply, it's ready to start working for you. It has an addressing capability up to 65K bytes, and comes 
with a user-dedicated 1K or 4K RAM. 

• Thermal Printer • Built-in Expansion Capability 

• Full-Size Alphanumeric Keyboard • TTY and Audio Cassette Interfaces 

• True Alphanumeric Display • ROM Resident Advanced Interactive Monitor 

• Proven R6500 Microcomputer System Devices • Advanced Interactive Monitor Commands 



PRICE: $37&ee 



(1K RAM) 



$369.00 



Plus $4.00 UPS (shipped in U.S. must give street address), $10 parcel post to APO's, FPO's, Alaska, 
Hawaii, Canada, $25 air mail to all other countries 

We manufacture a complete line of high quality expansion boards. Use reader service card to be added 
to our mailing list, or U.S. residents send $1.00 (International send $3.00 U.S.) for airmail delivery of our 
complete catalog. circ|e ig3 on inquiry card 




PRICE: $129.00 

We also carry the SYM-1 
Microcomputer with manuals $269.00 



VAK-1 MOTHERBOARD 

• Designed specifically for use with the AIM-65, SYM-1, and KIM-1 microcomputers 

• Standard KIM-4* Bus 

• Fully buffered Address and Data Bus 

• Provides 8 expansion board slots 

• Complete with rigid card-cage 

• All IC's are socketed 

• Provides separate jacks for one audio-cassette, TTY, and Power 

• Completely assembled (except for card-cage) 

We manufacture a complete line of high quality expansion boards. Use reader service 
card to be added to our mailing list, or U.S. residents send $1.00 (International send $3.00 
U.S.) for airmail delivery of our complete catalog. 
'Product of MOS Technology 

RNB> ENTERPRISES 

INCORPORATED 
2967 W. Fairmount Avenue • Phoenix, AZ 85017 • (602) 265-7564 



232 BYTE February 1980 



Circle 194 on inquiry card. 



When the people 

behind the products count! 



(Formerly the CPU Shop) 



TM 




X 




SPECIALS 



Regular 
Price 

32 K, quad-density, assembled and tested $2564 

32 K« quad-density, assembled and tested $3215 

$1895 
$ 149 



ComputerCity Sampler 
Disk Drives 



When you're ready to add disk storage to your TRS-80*, we're here to help. 
Our CCI-100"' and -200"' drives offer more capacity than Radio Shack 35-Track(85K Bytes) drives. These drives 
are fully assembled, tested and ready to plug-in the moment you receive them. They can be intermixed with each 
other and Radio Shack drives on the same cable. 90 day warranty. 
CCI-100"'' 40 Track (102K Bytes) $399.00 CC1-200"' 77 Track (197K Bytes) $675.00 



Printers 

Letter Quality High Speed Printer 

NEC Spinwriter: In- 
cludes TRS-80* inter- 
face software, quick 
change print fonts, 55 
CPS, bidirectional, 
high resolution plot- 
ting, graphing, pro- 
portional spacing and 

tractor feed assembly. 90 day warranty $2979.00 
Also: Centronics, Paper Tiger, HI Plot Digital Plotter 
16K Memory Op-grade Kits 

Fast and uitrareliable $99 .00 

DISK OPERATING SYSTEMS 
NEWDOS by Apparat + $49.95 

NEWDOS "PLUS" by Apparat" 1 " $99.95 

DOS 3.0 by the original author of 2.1 $49.95 




DISKETTE TRS-80* 

BUSINESS SOFTWARE BY SBSG 

Free enhancements and upgrades to registered 
owners for the cost of media and mailing. 30 day free 
telephone support. User reference on request. 
Fully Interactive Accounting Package: General Ledger, 

Accounts Payable, Accounts Receivable and Payroll. 

Report generating. 

Complete Package (requires 3 or 4 drives) $475 .00 

Individual Modules (requires 2 or 3 drives) $125.00 
Inventory II: (requires 2 or 3 drives) $ 99.00 

Mailing List Name & Address II 

(requires 2 drives) $129.00 

Intelligent Terminal System ST-80 III: $150.00 

The Electric Pencil from Michael Shrayer $ 1 50.00 
File Management System: $ 49.00 

Budget Control Program II by CSA $ 49.95 

Cash Register System II by CSA $ 99.00 



(ComputerCity 

A division of CPU Industries, Inc. 

1 175 Main Street, Dept. B-2Charlestown, MA 02129 , 

Hours: 10AM - 6PM (EST) Monday - Saturday 
For detailed information, call 617/242-3350 
Massachusetts residents add 5% Sales Tax 

TM CCI-lOO &-200 are ComputerCity Inc. trademarks 

"TRS-80 is a trademark of Radio Shack, a Tandy Corporation tRequires Radio Shack TRSDOS* 
Prices subject to change without notice - 



TO ORDER CALL TOLL FREE 1-800-343-6522 

Massachusetts residents call 617/242-3350 
Retail Store Locations: 



175 Main Street, Charlestown, MA 

K Mart Plaza, Manchester, NH 

50 Worcester Road(Rt.9), Framingham, MA 

165 Angell Street, Providence, Rl 

Visa and Master Charge accepted 

Franchise and dealer inquiries invited 



Circle 195 on inquiry card. 



BYTE February 1980 233 



Circle 197 on inquiry card. 



WAMECO 

THE COMPLETE PC BOARD HOUSE 
EVERYTHING FOR THE S-100 BUSS 

INTRODUCTORY SPECIAL 
IOB-1 SERIAL/PARALLEL INTERFACE BOARD 

* TWO PARALLEL DATA PORTS PROGRAMMABLE USING AN 8255 WITH SEPARATE 
HANDSHAKING. 

* ONE SERIAL PORT USING AN 8251 WITH PROVISIONS FOR PARITY, STOP BIT AND 
CHARACTER LENGTH. BAUD RATES 110 TO 9600 BAUD. OUTPUTS RS232, TTL 
AND CURRENT LOOP. 

* KANSAS CITY STANDARD CASSETTE INTERFACE, 300 BAUD FOR USE WITH THE 
SERIAL INTERFACE. 

* STATUS MAY BE POLLING SOFTWARE OR VECTURED INTERRUPTS. 

PCBD (SPECIAL FEB. PRICE) ......$29.95 AFTER FEB. ......$31.95 

KIT TO BE ANNOUNCED LATER. 

FUTURE PRODUCTS: 80 CHARACTER VIDEO BOARD. 
Z-80 CPU BOARD WITH RAM, ROM AND PROGRAMMABLE VECTOR INTERRUPTS. 

DEALER INQUIRIES INVITED, UNIVERSITY DISCOUNTS AVAILABLE 

AT YOUR LOCAL DEALER 

MOST PRODUCTS FOR IMMEDIATE SHIPMENT. NO 4-8 WEEK DELAYS REQUIRED FOR OTHERS. 



W77?C 



iflC. WAMECO INC. 111 GLENN WAY "8, BELMONT. CA 94002 (415) 592-6141 



>i 



CALIFORNIA COMPUTER SYSTEMS 

16K RAM BOARD. Fully buffered addressable in 4K 
blocks. IEEE standard for bank addressing 2114's. 

PCBD $ 26.95 Kit 450 NSEC ....$249.95 

PT-1 PROTO BOARD. Over 2,600 holes 4" regula- 
tors. All S-100 buss functions labeled, gold fingers. 
PCBD $25.95 

PT-2 PROTO BOARD. Similar to PT-1 except set- 
up to handle solder tail sockets. PCBD ...$25.95 

CCS MAIN FRAME. Kit (S-100) $349.95 

APPLE EXTENDER. Kit $22.95 

APPLE IEEE INSTRUMENTATION INTERFACE 
KIT 7490. Kit $275.00 

ARITHMETIC PROCESSOR FOR APPLE 7811A. 
Kit $350.00 

APPLE ASYNCHRONOUS SERIAL INTERFACE 
7710A. Kit $89.95 

APPLE SYNCHRONOUS SERIAL INTERFACE 

771 2A. Kit $89.95 

ALL OTHER CCS PRODUCTS AVAILABLE 



==/n 



PB-1 2708 & 2716 Programming Board with pro- 
visions for 4K or 8K EPROM. No external supplies 
require textool sockets. Kit $129.95 

CB-1A 8080 Processor Board. 2K of PROM 256 
BYTE RAM power on/rest Vector Jump Parallel 
port with status. Kit ....$129.95 PCBD $30.95 

VB-3 80x55 VIDEO BOARD. 

Graphic included TBD 

IO-4 Two serial I/O ports with full handshaking 
20/60 ma current loop: Two parallel I/O ports. 
Kit $130.00 PCBD $26.95 

VB-1B 64 x 16 video board, upper lower case Greek 
composite and parallel video with software, S-100. 
Kit $125.00 PCBD $26.95 

CB-2 Z80 CPU BOARD. Kit $185.95 

AIO APPLE SERIAL/PARALLEL $159.95 

ALL OTHER SSM PRODUCTS AVAILABLE 



W7T7C 



inc. 



WAMECO INC. 



FDC-1 FLOPPY CONTROLLER BOARD will drive 
shugart, pertek, remic 5" & 8" drives up to 8 drives, 
on board PROM with power boot up, will operate 

with CPM™ (not included). PCBD $42.95 

FPB-1 Front Panel. IMSAI size, hex displays. Byte, 

or instruction single step. PCBD $47.50 

MEM-1A 8Kx8 fully buffered, S-100, uses 2102 

type rams. PCBD $25.95 

QM-12 MOTHER BOARD, 13 slot, terminated, S-100 

board only $34.95 

CPU-1 8080A Processor board S-100 with 8 level 

vector interrupt. PCBD $26.95 

RTC-1 Realtime clock board. Two independent in- 
terrupts. Software programmable. PCBD $23.95 

EPM-1 1702A 4K Eprom card. PCBD $25.95 

EPM-2 2708/2716 16K/32K EPROM CARD. 

PCBD $25.95 

QM-9 MOTHER BOARD. Short Version of QM-12. 

9 Slots. PCBD $30.95 

MEM-2 16Kx8 Fully Buffered 2114 Board 

PCBD $26.95 

PTB-1 POWER SUPPLY AND TERMINATOR BOARD 

PCBD $25.95 

8080A $9.95 2708 $9.49 

8212 2.49 2114 (450 NS) low pwr 5.99 

8214 4.49 2114 (200 NS) low pwr 6.99 

8224 3.49 2102A-4L 1.20 



m& 




(415) 592-1800 
P. O. Box 424 • San Carlos, California 94070 

Please send for IC, Xistor and Computer parts list 



FEB. SPECIAL SALE 
ON PREPAID ORDERS 

(Charge cards not included on this offer) 

IOB-1 SERIAL/PARALLEL INTERFACE BOARD. 
Two parallel ports 8255, one serial port 8251, 
one Kansas City standard cassette. 

PCBD (Introductory) $24.95 

UIKOS PARTS ASSORTMENT 
WITH WAMECO AND CYBERCOM PCBDS 
MEM-2 with MIKOS s 7 16K ram 

with L2114 450 NSEC - $249.95 

MEM-2 with MIKOS =13 16K ram 

with L2114 250 NSEC - $279.95 

MEM-1 with MIKOS *1 450 NSEC 8K 

RAM $1 1 9.95 

CPU-1 with MIKOS *2 8080A CPU $ 94.95 

QM-12 with MIKOS *4 13 slot mother 

board $ 89.95 

RTC-1 with MIKOS *5 real time clock $ 54.95 

EMP-1 with MIKOS *10 4K 1702 less 

EPROMS $ 49.95 

EPM-2 with MIKOS =11 16-32K EPROMS 

less EPROMS $ 59.95 

QM-9 with MIKOS "12 9 slot mother 

board $ 79.95 

FPB-1 with MIKOS s 14 all parts 

for front panel $134.95 

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY MARKED 
PARTS. KITS INCLUDE ALL PARTS LISTED AS REQUIRED 
FOR THE COMPLETE KIT LESS PARTS LISTED. ALL SOCK- 
ETS INCLUDED. 



VISA or MASTERCHARGE. Send account number, interbank num- 
ber, expiration date and sign your order. Approx. postage will 
be added. Check or money order will be sent post paid in U.S. 
If you are not a regular customer, please use charge, cashier's 
check or postal money order. Otherwise there will be a two- 
week delay for checks to clear. Calif, residents add 6% tax. 
Money back 30-day guarantee. We cannot accept returned IC's 
that have been soldered to. Prices subject to change without 
notice, sio minimum order. SI. 50 service charge on orders 
less than $10.00. 



234 BYTE February 1980 



Circle 196 on inquiry card. 



TRS-80 COMPATABLE 
DISK DRIVES 



The largest 




family of 




disk drives 




from the 




largest a 




supplier, 




drives come I 




complete 1 




with power 1 




supply and I 


... ■. . , \ 


cabinet 





18 ■ 'W9BM0B 

■ ■,: 

■ : ■ ■.■ ■ . 



TF-1 Pertec FD200, 40 track 

TF-3 Shugart SA400. same as tandy . 

B51 MPI 851, 40 track 

TDM Dual Head, 35 track 






$382 
$389 
$379 
$499 



220 versions available. 

NOW! SUPER & MAX 
DISKS 

SUPER: 77 tracks on one 5 : A diskette that's 197K of storage 
with New DOS+ $695 

MAXI DISK I: 10 Megabyte hard disk with 5fixed 5 removable 
with controller $6299 

MAXI DISK II: 9.8 Megabyte on one disk using Winchester 

technology. Unit is sealed in unit for added 

protection $5349 



SOFTWARE 



NEW DOS+ over 200 modifications, corrections 
and enhancements to TRS DOS Includes utilities. 

35 Track NEWDOS+ $99 

40 track NEWDOS+ $110 

AJA Word Processor $75 

AJA Business Program $250 

Racet Infinite Basic $49.95 

Disk Drive Alignment Program $109 

Radex Data Base $99.95 

Electric Pencil $1 50 




BASE 2 
ONLY 

$599. 



LINE PRINTERS 

ST 



The new base 2 printer, prints 60 Ipm, 80 & 132 col. formats. It 
has tractor feed w/RS232, IEEE & centronic interface. 

DP800 ANADEX 80 column, 112 cps $950 

LP779 Centronics 779 $1099 

LP730 Centronics 730 $950 

LP700 Centronics 700 $1495 

LP701 Centronics 701 $1 759 

LP702 Centronics 702 $1895 

Spin-1 Spinwriter $2499 

MOD II DISK DRIVES NOW AVAILABLE 



ADD-ON DRIVE FOR 
ANY MICROCOMPUTER 

Pertec FD200 .. . 

Pertec FD250 (dual head) J 282 

Shugart SA400 (unused) * 349 I 

Shugart SA800 $286 

MPI B51 $479 

MPI B52 (dual head) $ 279 

$349 I 



NEW PRODUCTS 

Small Systems Interface (RS232) $49.95 

Expansion Interface W32K $499.95 

AC Line Filter $18.95 

AC Isolater (6 connecters) $45.95 

Mode M $1 79.95 

Verbatim 5'A Diskettes $3.39 

16 Key Pad Kit (no soldering) $68 

16K Memory (Keyboard) $89 

16K Expansion (Interface) $86 



ALL PRICES CASH DISCOUNTED • FREIGHT FOB/FACTORY 



»in 



/MICROCOMPUTER 

TECHNOLOGY 
INCORPORATED 

3304 West MacArthur Blvd 

Santa Ana, CA 92704 

(714) 979-9923 





^^ m 


i 


visa m 




master charge] / , 




THE IMTCR8ANK CARD k § j 






\ 






1 m 



7310 E. Princeton Ave. 
Denver, CO 80222 
(303) 758-7275 

pparat, Inc. 



Circle 198 on inquiry card. 



Circle 199 on inquiry card. 



BYTE February 1980 235 



Circle 200 on inquiry card. 




computer 
products, 



11542-1 KNOTT ST. 

GARDEN GROVE, 

CA 92641 

(800)854-6411 

(714)891-2663 



MICROBYTE 
16K RAM BOARD 



• FULLY S-100 
COMPATIBLE 

• USESLO-PWR 
4KX1, MM5257'S 

•2MHZ0R4MHZ 
•4KBANK 

ADDRESSABLE 
•EXTENDED MEMORY 

MANAGEMENT 
•NO DMA RESTRICTIONS 
•ASSEMBLED & TESTED 
2MHZ$250-4MHZ$265 



MICROBYTE 
32K RAM BOARD 



REGULATORS 



320T-5. . 
320T-12. 
340T-5. . 
340T-12. 
78H05 . . 
78L12 .. 



.90 
.90 
.80 
.70 
.4.75 
. .35 



• FULLY S-100 
COMPATIBLE 

• USESLO-PWR 
4KX1,MM5257's 

•2MHZ0R4MHZ 

• BANK ADDRESSABLE 

• EXTENDED MEMORY 
MANAGEMENT 

•8-BIT OUTPUT PORT 
•NO DMA RESTRICTIONS 
•ASSEMBLED & TESTED 
2MHZ$525-4MHZ$540 



MISC. COMPONENTS 



IMSAI CONNECTORS 

100 PIN-SOLDERTAIL 

$3.00 each 
10 for $2.75 each 



LM339 . . 




LM348.. 


.1 


LM377.. 


.1 


LM380.. 




LM3900. 




DM8216. 


.2 


8080A . . 


.4 


8251 ... 


.5 



1-9 

70 
00 
10 
80 
55 
10 
50 
00 



10-99 

.65 

.92 

1.00 

.75 

.50 

2.00 

4.25 

4.80 



100 up 

.59 
.85 

.95 

.70 

.44 

1.90 

1.00 

4.50 



LO-PRO SOCKETS 



14 PIN 
16 PIN 

18 PIN 
20 PIN 
24 PIN 
28 PIN 
40 PIN 



1-24 

.15 
.16 
.19 
.27 
.35 
.40 
.50 



25-99 100 up 

.14 .13 



.15 
.17 
.25 
.31 
.33 
.46 



.14 
.15 
.23 
.27 
.29 
.41 



4116's 

(250NS) 

ADD ON MEMORY 

FOR APPLE, TRS 80, 

HEATH, ETC. 

8 for $64.00 

or 

16 for $120.00 



SA800 DRIVE 

INSTALLED IN DUAL 

CABINET W/PWR SUPPLY 

ASSEMBLED & TESTED 

(1) DRIVE INSTALLED 

$695.00 

(2) DRIVES INSTALLED 

$1125.00 



ASK 
FOR 
OUR 
NEW 
CATALOG 



271 6's 

5- VOLT ONLY 
450 NS. 

$32.00 ea. 

or 

8 for $240 



ORDERING INFO 



NAME, ADDRESS, PHONE 

SHIP BY: UPS OR MAIL 

SHIPPING CHRG: ADD $2.50 

UP TO (5) LBS, CREDIT CARDS 

WILL BE CHARGED 

APPROPRIATELY 



2708's 

450NS 
$8.50 

or 

8/$60 



CERAMIC 
CAPS 

.1 @ 12 VOLTS 

10« ea 

or 

100/$9.00 



2114's 



LO-PWR 
300 NS. 

1-16 PCS. 

$5.25 ea 

17UP 
$5.00 ea 



TERMS 



WE ACCEPT CASH, 

CHECK, MONEY ORDERS, 

VISA & MASTER CHRG. 

(U.S. FUNDS ONLY) 

TAX: 6% CALIF. RES. 






DIGITAL 
MULTIMETERS 

HickokLX303*69 5 ° 





Sinclair PDM35 

Reg. S69.95 

$ 49 95 , 



3%-Digit "-SJS 
Portable DMM 




Tmuraphone 

Cordless 

Telephone 

System 

Reg. S89.95 
$7495 




'/ • Overhead Protected • 
Battery or AC operation • 
3" high LED Display • Auto 
zeroing 



Portable Oscilloscopes/** 
15 MHz am ■ g »*F 
Dual Trace 
Triggered »« 
Miniscope WaV 



$ 369 95 s, Res 




Model MS-215 

S435.00 

15 MHz Triggered Miniscope 

Model MS-15 RegS319 00j«eQ95 

30 MHz Dual Trace 
Triggered Miniscope 

Model MS-230 R?g S559 00*479^ 



Logic Probe 

■ Compact circuit powered ■ 
Detects pulses as short as 50 
,isec. DTLTTLHTL'CMOS, 
compatibility $4495 

RC Circuit Box 

• 36 resistors (15!! 
to 10MUI ■ 18 
capacitors (100 pt to 

Reg S49 95 t^. 

includes test leads 




Model 
LP-1 



Chess 

Challenger 7 *''•:<&■* 

Reg S99 95 Mo( j e | I ■™cj"u.ji„ 
$7490 BBC I 



Function 
Generator 



Model 2001 
Reg. $185.95 
S 157 95 

■ Sine-, square-. 
Iriangle- and 
separale TTL 
square wave 
output ■ 

Frequency range: 
IHz-IOOKHz 



Portable VOM 
Multitester 

Model $1Q95 
VM520 I •» 

20K!i VDC 10KS1 VAC 




HICKOK 

Digital CB In-Line 
Tester 



$ 169 95 , 

Reg. S399.00 




100 MHz 8-Digit Counter 

• 20 Hz to 100 MHz M J del ™* X 1S° rS 
range. LED display "j°J 15l L" 

• Fully automatic *"J 2/ 







Logic MonitorTTelephone 



Automatically 
displays static and 
dynamic logic • 
Model LM-1 Works with DTL. HTL, 
SCQ95 TTL. and CMOS • 16 



LED display 



Attache 
Style 
Tool Case 

Model TC100 ST 

A $ 279 95 

Service 
Master 
Tool Kit 

Model 99-SM 
S6 R 9 C 9 9 S $ 47 50 



Weller'-Xcelite" 




Model 820 
Measures 
capacitance 

from 0.1pF to 1 Farad ■ Resolves to 
O.lpF ■ 10 ranges for accuracy and 
resolution ■ A digit easy-to-read LED 
display ■ 0.5% accuracy 

*=S=3V 2 -Digit0.1% Digital 
Capacitance Meter Model 3001 

• 9 ranges Irom 1999 pF to 199.9 W F 
0.1% of reading accuracy „„ R eg $-i "7CI 



Proto E^B 
Preassembled 
r^ei ^k Boards 

PB-104>Ss | "**49 9b 

Fully assembled breadboard 
contains lour QT-59S sockets, 
seven QT-59B bus strips and four 
5-way binding posts 




Proto Board with 
Built-in Power 
Supplies 




i129 M S& 



30 MHz LEADER 
Dual Trac e 

$ 899 95 

Model LBO-520 




Weller'Controlled 
Output Soldering 
Station 




BSS2MS3 Portable 
Digital C apacitance 
Meter ( % .,, 




6"x9" 3- Way Speaker 

■ 20 oz. ceramic magnet 
Model BP2000-69TR 

$ 14 95 ea. 



CODEvl-PHONE 



Answering 

Model 1500 $0*Q95 
Call Control ^£f\y^ 
Reg S349 95 __ 

*199 95 



Model 1-1011 




t 

r^Beckman 
TECH 
310 

^130. 



WAHL 

!^™ Cordless 
60 Soldering 
vw Iron 
$2995 

Model 7800 



Thenmcd-Spat 

Circuit Tester »29 95 




Miniature High Fidelity 
3-Way Stereo Speakers 

$CQ50 Re 9 S149.95 




Model 
HF-9 



S190.00 



y Simpson 461 

. Iu i(fca^ Complete with nickel- 
iAi:.^L A cadmium batteries, AC 
charger adapter, test 

leads $ 149 95 





In-Dash Car Stereos 
8-Track Tape Player with 
AM/FM/MPX Radig_ 

Model C-777 f 

$ 52 5o 



Cassette Tape Player 
with AM/FM/MPX Radio 

Model K " "~ 

CAS-888 \ g = 

$ 57 50 i^SiS 



Tr 



BSRX-10 

is 



Remote Control for 
Lights & Appliances 




•1 Pc S1.ind.itd Starter Kil • One (1) Standard Command Reg £67 95 
Console ■ Two (2i Lamp Modules ■ One (I) Apnhanee S7Q50 
Module I !7 

5 Pc Ultrasonic Starler Kil - One 11} Deluie Ullwsnmc Reg SH2 3: 

Commjiiti Console" One tit Hand Held Remote Unit ■ Two j| ' 

l?l Lamp Module ■ One 1 1 1 Appliance Umi 



Lamp Modules $14.50 Standard Command Console S36.00 

ipUanca Modules $14.50 Uttosonic Command Console ce Q qc 

■ •■ • . S14 SO ■■■ ' ■ ■ m.mP.i--. - 



BMBBm mhz 

Portable Frequency 
Counter neg smM 




Stereo Power Booster Z^'-'-'w. 

Model POW-40 SO/IIS Histu^, 

.40W stereo >24 yS MSSQ 



236 BYTE February 1980 



855 Conklin St. Farmingdale, NY. 1 1735 
■ Master Charge ■ BankAmericard ■ VISA 
4 ■ COD ■ Check ■ Money Order 

N.Y. State residents add appropriate sales tax 

free(800)645-9518 

in N.Y. State call (516) 752-0050 



Circle 201 on inquiry card. 



10-DAY FREE TRIAL 



Send for our 
FREE Catalog 



$100 FREE ACCESSORIES 
WITH 16K or 32K PET 

When you buy a 16K or 32K PET, apply $100 toward PET 
accessories, FREE. Just indicate on your order that you have 
reduced the cost of your accessories by $100. 

Terminal Package with 8K PETs 

See Special Below 

PET ACCESSORIES 



FftEt 



V 



8K-Keyboard N $795 

16K-Keyboard B $905 

16K-Keyboard N $995 

32K-Keyboard B $1,295 

32K-Keyboard N $1,295 

B — large keyboard (graphics not on keys) 
N — large keyboard with graphics symbols 



SANYO MONITORS 



9-inch 
reg $240 

SALE! $169 




Commodore Dual Floppy Disk Drive $1,295.00 

Commodore Printer (friction feed) S849.00 

Commodore Printer (tractor feed) S995.00 

Second Cassette- from Commodore $95.00 

Commodore PET Service Kit $30.00 

Beeper-Tells when tape is loaded $24.95 

Petunia- Play music from PET $29.95 

Video Buffer-Attach another CRT $29.95 

Combo-Petunia and Video Buffer S49.95 

TNW Bi-Dir. RS-232 printerX-face . . $229 

KIM 1 (A Single Board Computer 

from Commodore) $179.00 



PET OWNERS 



Hazeltine 1400 

Immediate Delivery — 
? \ 2-Year Factory Warranty 

'LIST SALE 

$8C$ $649 



Hazeltine 1410 
Hazeltine 1500 



- $835 
$1069 



Hazeltine 1510 — $1195 
Hazeltine 1520 — $1499 



SALE! $279 




^>n 



apple II 

200 Ffi€€ fKC€SSORI€S 

The new Apple II with Applesoft BASIC built-in! Elimi- 
nates the need for a $200 Firmware Card and includes 
new Autostart ROM for easy operation. This combined 
with the FREE accessories from NCE could save you up 
to $400 on a 48K Apple II system! 

1 6K Apple II Plus — $1 195 (take $100 in free accessories) 
32K Apple II Plus — $1345 (take $150 in free accessories) 
48K Apple II Plus — $1 495 (take $200 in free accessories) 

Apple II Accessories 

General Business $625 

PASCAL $495 

Integer BASIC ROM Card $200 

VISI-Calc $149 

Centronics Printer Interface $225 

Disk and Controller $595 

Parallel Printer Card $160 

Communications Card $225 

Hi-Speed Serial Card $195 

Firmware Card $200 



IN STOCK NOW! 

EVERY ITEM IN THIS ADVERTISEMENT IS IN STOCK 
AND READY TO SHIP, EXCEPT WHERE NOTED. 



PAPER TIGER 440SPE 

The Graphics Printer 
for Appie ii 

Now you can print illustrations, block letters, charts, 
graphs, and more — all under software control- And 
with the expanded buffer, the Paper Tiger can hold the 
text from an entire 24-line-by-80-column CRT screen. 

$1194.00 



NCE/CompuMart «S 

DEPT.KB20, 270 THIRD ST., 
CAMBRIDGE, MA 02142 

To Order: 1 (800) 343"5504 
In Mass: 1 (61 7) 491 "2700 



REMOTE 
TERMINAL 

for 
only $98 

A self-contained 
module and program 
cassette enables your 
PET to function as a 
300 baud terminal. 
Supports Upper/Lower 
case, Rubout, Escape 
& all control functions. 
Output is TTL. 

WITH 

PET 

PURCHASE 



Lear Siegler's ADM-3A 



The ADM-3A is industry's favorite dumb terminal for 
some very smart reasons: 

• 12 in. diagonal screen 

• Full or half duplex operation at 11 selectable data 
rates 

• 1920 easy-to-read characters in 24 rows of 80 letters 

• Typewriter-style keyboard 

• RS-232 C interface extension port 

• Direct cursor addressing 

Our Low Sale Price $795 



COUPLER! 



New 300 baud 
Originate/Answer 
Acoustic Coupler 
Looks good, works 



^ ZENITH COLOR 
* VIDEO MONITOR 

Zenith's first color video display 
designed specifically for computers. 

This 13-inch monitor is Zenith's first color video display 
designed specifically for computers. Features include 
automatic color level, color processing and degaussing 
circuits. 

Zenith Color Monitor $499.00 



$189 



from Heath Data Systems 



The All-in-One Computer 

Dual Z-80 Processors • Built-in 102K Floppy Disk • 16K 
to 48K RAM ■ 25 x 80 Character Display • Upper/Lower 
Case and Line Graphics • 80 Character Keyboard with 
Keypad ■ 8 User-definable Keys • Two BASIC'S and 
Auto-Scribe Word Processing available • Can support 
CP/M 

Heath's third generation of computers is a compact, 
hi-style desktop unit which includes a complete termi- 
nal, a computer and a disk All-in-One! System includes 
Bootstrap in ROM, other programs available separately. 
HDOS operating system includes Heath's BASIC, an as- 
sembler and text editor along with important disk 
utilities. Microsoft language requires HDOS. 



WHB9 with 16K RAM $2,295 

WHB9 with 32K RAM $2,445 

WHB9 with 48K RAM $2,595 

WH1 7 Second Disk Drive $550 

Dual-port Serial Interface $85 

HDOS Operating System $100 

Microsoft BASIC $100 

Word Processing $395 



<F 



& 



Just Released 



Compumart's New 
Fall/Winter 1979 Catalog. 

We've just published our catalog and its packed with 
new products and money saving specials. Our 
illustrated 32-page book features microcomputers and 
microcomputer systems from Apple, Commodore PET, 
Heath, and Exidy Sorcerer. Also covered are the 
Commodore's KIM and Rockwell's AIM. A broad 
selection of terminals, books, software and peripherals 
are presented in detail. The text is thorough and 
provides a wealth of technical information. To get your 
FREE copy write to our address below. Please include 
the dept. number to speed handling. 



CENTRONICS 779-2 PRINTER 



TRACTOR FEED 

Parallel interface 
Continuous variable 
printing density 80-132 
characters per line 
5x7 dot matrix 



SALE PRICE $1095 

Form thickness control 
Horizontal and vertical 
form positioning 
Used with controller 
(Apple general 
business software) 
JUST ARRIVED. We've just received shipments of (he 
following Centronics printers. Call us for complete 
specs. 

730-1 S995 

730-3 SI 045 

753-9 (9*9 Matrix) S2,795 704-9 {9*9 Matrix) $1,995 



SINCE 
1971 



IMPORTANT ORDERING INFORMATION 

All orders must include 4% shipping and handling. Mass. residents add 5% sales tax; Mich. 

residents 4%, for sales tax. 



Phones open from 8:30 a.m. to 5:30 p.m. EST Mon.-Frl. • P.O.'s accepted from D&B rated 
companies — shipment contingent upon receipt of signed purchase order • Sorry no C.O.D.s • 
All prices are subject to change without notice • Most items in stock for Immediate shipment — 
call for delivery quotation • In the Ann Arbor area? Our retail store Is open 11:00 a.m. to 7:00 p.m. 
Tues.-Frl., 10:00 a.m. to 5:00 pm. Saturdays (closed Sun. and Mon.) 



VISA 



Member: .*..•,.«. m , .. 

Computer Dealers If not satisfied, return your purchase with-in 10 days for full 

Association refund of purchase price! 



Circle 202 on inquiry card. 



BYTE February 1980 237 



page 



Precut Wire Wrap Wire 

PRECUT WIRE SAVES TIME AND COSTS LESS THAN WIRE ON SPOOLS 



Kynar precut wire. All lengths are overall, in- 
cluding 1" strip on each end. Colors and 
lengths cannot be mixed for quantity 
pricing. All sizes listed are in stock for 
immediate shipment. Other lengths 
available. Choose from colors: Red, Blue, 
Yellow, Orange, Black, White, Green and 
Violet. One inch tubes are available at 500. 
State second choice on colors when pos- 
sible. 



Length 


100 


500 


1,000 


Length 


100 


500 


1,000 


2.5 inches 


1.04 


2.98 


5.16 


6.5 inches 


1.60 


5.37 


9.84 


3 


1.08 


3.22 


5.65 


7 


1.66 


5.63 


10.37 


3.5 


1.13 


3.46 


6.14 


7.5 


1.73 


5.89 


10.91 


4 


1.18 


3.70 


6.62 


8 


1.78 


6.15 


11.44 


4.5 


1.23 


3.95 


7.12 


8.5 


1.82 


6.41 


11.97 


5 


1.28 


4.20 


7.61 


9 


1.87 


6.76 


12.51 


5.5 


1.32 


4.48 


8.10 


9.5 


1.92 


6.93 


13.04 


6 


1.37 


4.72 


8.59 


10 


1.99 


7.26 


13.57 



Kit #1 S7.95 
Less than 2.7C/H. (#30) 


Kit #2 
Less than 


$19.95 
2C/ft. (#30) 


KIT #3 $24.95 
Less than 1.7C/M. (#30) 


Kit #4 $44.95 
Less than 1.6C/ft. (#30) 


#30 Spools 
1-4 


5-9 10+ 


250 3" 100 4" 
250 3" 100 5" 
100 4" 100 6" 


250 2'/?" 
500 3" 
500 3'/s" 
500 4" 
250 4'/ 2 " 


250 5" 
100 S'A" 
250 6" 
100 6 1 //' 
100 7" 


500 2Vi" 
500 3" 
500 3'/?" 
500 4" 


500 AW 
500 5" 
500 5V4" 
500 6" 


1000 2'/ 2 " 1000 4W 
1000 3" 1000 5" 
1000 3V 2 " 1000 5" 
1000 4" 1000 6" 


50 ft. 1.75 

100 ft. 3.00 

250 ft. 4.75 

500 ft. 8.50 

1000 ft. 14.50 


1.60 1.40 
2.75 2.50 
4.50 4.25 
8.00 7.50 
12.50 10.50 



Wire Wrap Tool 

BATTERY HOBBY TOOL* BW2630 Tool $19>85 

• Autolndexing BT30 * 30 Bit 2 - 95 

• Anti-Overwrapping BT2628 #26 Bit 7.95 

• Modified Wrap BC1 Batteries & Charger. . . 11.00 

* Requires 2 "C" Nicad Batteries 



Solderless 
Breadboarding 

SK10 2/S25.00 _5i&6e- 

The SKIO's unique matrix config- 
uration is embedded in a high temp- 
erature plastic molding. It gives you 64 
pairs of 5 common spring contacts for 
principle circuit construction and a 
series of common buss strips (8) of 25 
connections each. 
Dimensions: ,33"h x 2.2"w x 6.5"l 




IC 
Sockets 



RN HIGH RELIABILITY eliminates 
trouble. "Side-wipe" contacts make 
100% greater surface contact with the 
wide, flat sides of your IC leads for 
positive electrical connections. 



AVAILABLE AT SELECTED LOCAL DISTRIBUTORS 




Tl Edge Card 
Connectors 

44 pin ST (.156" centers) 
100 pin ST (.125" centers) 
100 pin WW (.125" centers) 

All connectors gold plated. 




WIRE WRAP 


Size 


Quant./Tube 


Price Ea. 


Price/Tube 


SOCKETS 


08 pin 


WW 52 


.31 


$16.12 


3-level Gold 


14 pin 


60 


.32 


$19.20 


Closed Entry Design 


16 pin 


52 


.34 


$17.68 


All prices include Gold 


18 pin 


23 


.50 


$11.50 


2-level Sockets 


20 pin 
22 pin 


21 
19 


.65 
.70 


S13.65 
$13.30 


Also Available 










Sockets sold at these 


24 pin 
28 pin 


10 
10 


.70 
.95 


$7.00 
$9.50 


prices by the tube only. 


40 pin 


7 


1.20 


$8.40 



ORDERING INFORMATION 

• Orders under S25, add $2 handling 

• Blue Label or First Class, add $1 (up to 3 lbs.) 

• CODs, VISA & MC orders will be charged shipping 

• Most orders shipped next day 



D32,© 135 E. Chestnut Street 5A, Monrovia, California 91016 Phone (213) 357-5005 



Circle 203 on inquiry card. 



CaMFornja DiqiTAl 

Post Office Box 3097 B • Torrance, California 90503 




software selectable character sizt 
characters per line. Full forms 
feed mechansim adjustable to 9.5' 
to accept either parallel or RS232 
***** $995.00 plu 



CONNECTORS 



imiuiuu. 



3= 



°m 



m\ 



your choice 

DB25P 

male plug & hood 

or 

DB25S female 

«3.25 

Qty. fe. male hd. 
10 3.05 1.95 1.15 
25 2.95 1.79 1.05 
100 2.65 1.S7 .95 
500 2.25 1.60 .85 
IK 1.97 1.37 .73 



With Purchase of The 
INTEGRAL DATA 440 

Paper Tteer 

Your Choice, $200 Value 

1) Graphics Option Package 

2) Interface for APPLE II 
3JTRS-80 Printer Interface 

California Digital has resently 
researched the complete low 
cost printer market. It is our 
opinion that the IDS 440 Paper 
Tiger is, without doubt, the 
most versatile and offers the 
best value of any printer cost- 
ing under $1,000. 

This quality dot matrix printer 
incorporates such features as 
■ to allow print densities upto 132 
handling capabilities and tractor 
'. The Paper Tiger is engineered 
serial ASCII. 110/220V.50/60Hz. 
s shipping ***** 



Edge 
Connectors 




GOLD 
100 PIN 

IMSAI/ALTAIR 

Imsai solder 125*250 i2.95 3/4 7.50 

Imsai w/w.l25centers (4.95 3/113.00 

Altair soldertail.l40row $5.95 3/(15.00 

SPECIALS 

22/44 Kim eyelet. 156" SI. 35 3/45.00 

25/50 solder tab .156" 41.09 3/42.00 

36/72 wide post w/w.156 41.95 3/45.00 



Authorized Distributor lOPak 50*- 

O^.^i^-LJ 740-0 IB M soft format. $39.00 $3.50 

OCOT.Cn ' ! " Double sido soft 65.00 6,00 

Dataproducts 741-0 Double density 53.00 4.90 

743-0 Double/Double 70.00 6.60 

740-32 8" Hard sector 39.00 3.50 

744-(0)<10)(16) 5 l/4"miru 39.00 3.50 
Library case for any above; Add $3.00 

834 A Data Cassette 5.50 

DC 100 Minicartridge 16.00 

DC 300 Data Cartridge 20.00 

920( ) Disk Cartridge 89.00 



S-100 Mother Board 



Quiet 
Boss 




18 slot 
IMSAI 



Minidisk Drive f or TRS-80 

your choice tff^QQ 

J4> tacSs 
VlSta Interface Cable 



TELETYPE MODEL 43 



4320 KEYBOARD 

TTL AAA $1050 

RS232....AAK 1150 

Friction . . . AAE 

103 Modem AAB 1575 




1100 shipping 



Ta? 



rnrr PLASTIC LIBRARY CASE 

rll PP with purchase of each box of .... 



Verbatim mini-diskettes. J5 value. 




DISKETTES 




It's not iiITlti that Caiifon 
aires into ilit-' distribution 
ducts, but we have resently c 
a product that appeal's bo unique that we just had to add It 
to our product line. T his is the System x-10 manufactured 
by llV HSU turntable company. This space ace system will re- 
motely control any light or appliance in your home or offices Command sig- 
nals are transmitted from the command console over your existing wiring. 
From your bed or easy chair you can control up to IG different electrical de- 
vices inside and uulside your home. Use the System X-10 to control your 
stereo, television or any lifiltt fixture on the premises. 

['he modular system is available in the following components; 

Ultrasonic Master Control Console §34. 05 

Battery Iterated Ultrasonic Controller 19.95 

Appliance Module. Lamp Module or Wall Switch 13. 95 



SPECIAL 



APPLE II 

I6K MEMOR' 

COLOR • GRAPHICS* SOUND 

$988 

PLUS SHIPPING 



Mfg.Sng. 
Retail.... 



9 



■ Shugart Associates 



SA800-R Floppy Disk Drive 

Fhe most cost effective way to store data proc- 
essing information, when random recall is a 
prime factor. The SA800 is fully compatible 
with the IBM 3740 format. Write protect cir- 
cuitry, low maintenance & Shugari quality. 



$44350 



KEYBOARD 

ASCII ENCODED 




KEYTRONIC 
ASCII & ASCII 
complement. 
*Ten key data pad I 
♦Cursor controls 
*Six user swi;ches| 

* Alpha Lock 

*Auto repeat 

♦Single 5 volt. 

*Glass reed. 

NEW 



MEMORY 



TRS-80 Sj 
APPLE II 

16k memory (8)4116's 



Installation is simple. Anyone who has 
ever changed a spark plug should be able < 
to up-grade his microcomputer. 
How can California Digital offer these 
memory up-grade sets at 25% below our competition? 
Simple, we buy in volume, wholesale to dealers and 
sell the balance directly to owners of personal micro- 
systems. These 16K dynamic memory circuits are 
factory prime and unconditionally guaranteed for one 
full year. NOW, before you change your mind, pick 
up the telephone and order your up-grade memory 
from California Digital. Add $3 for TRS80 jumpers. 




STATIC 1-31 

21L02 450nS. 1.19 

21L02 250nS. 1.49 1 

2114 1KX4 450 5.95 5 

2114 1Kx4 300 8. 95 8 

1044 4Kxl 450 5.95 5 

4044 IKxl 250 9.95 9 

4045 1Kx4 450 8. 95 8 
4045 1Kx4 250 9.95 9 
5257 low pow. 5. 95 5 

SPECIAL CIRCUITS 

Z80A 4 MHz. 24.95 

8080A CPU 9. 95 

8085 22.50 

8086 Intel 16 bits 85. 00 
T.MS 9900 16 bits 49.95 



32-99 100-5C 



999 
, 90 



1K+ 
.85 



. 39 

.50 
.50 

.50 
. 50 
. 50 
. 50 
. 50 



1. 25 
5. 25 
8. 0D 
5. 25 
9.00 
8. 00 
9.00 
5.00 



4.80 4.60 



AY5-1013A UART 4.95 
Floppy Disc Controllers 
WD 1771 single D. 39. 95 
WD 1781 Double D 65. 00 
WD 1791 D/D3740 * 



E PROMS 1-15 16-63 64+ 

1702A 2K 4. U5 4.50 4.00 

2708 8K 9. 95 9.50 9.00 

2716 5vl6K 39.95 35.00 * 

2716 T I 24.38 20.00 * 

2532 85.00 * * 



> J fi<{fP)i( 



^•^nJi^ 



r 



byapt= 

A BRILLIANT 

computer cyine 

WHOSE TIME * P *Kji3 
HAS COME. " 




Miniature 
Switches 

Iff 

$.98 $.88 .81.73.66 
SPDT Miniature Toggles 

7101 C&K 0N-N0NE-0N 

7107 jbt ONOFF(mnt.ON) 

7108 CK OrHmomenl ON) 
7103 CK ON OFF ON 
Rotary 3P-4Pos. 
Rotary 3P-6Pos. 
Push B IN 0.) S. 39 u.i. 4 S 1 



your choice 

50 1001k 



DIP Switch 




s l? 9 



25 100 IB 




PORTABLE DATA ENTRY SYSTEM 



terminals nwe originally designed for chain store inventory con- 
niry systems. The operator enters the inventory control number, 
hand and the unit price. After all pertinent data has been entered into 
le recorder, the main warehouse is telephoned, the handset is placed in the tcoustic 
jupler and all the recorded information Is transmitted hack to the master computer, 
ith a Iiiilf invagination and one of these portable entry systems, you 
i exchange programs and computer information with associates aero; 
units «ere removed from service in working condition. Original t 

table Cassette Drive Unit -Five Could "IJ" NtCads >UB: 

lovable Entrv Keyboard "Acoustical Coupler .Shoulder st 

ill, LED Display 'Batten- Charger •Full Docun 



trol and c 



All 



should be able 
is the country. 

ost 52.500. 
tS Cable 



DISCOUNT ' | 

Wire UU rap Center 



IC SOCKETS 



wire wrap 
ea. 25 50 


low profile 
ea. 25 50 




17< 16 15 




37<36 35 


18 17 16 


38 37 36 


19 18 17 


99 93 85 


36 35 34 


169 155 139 


63 60 58 



5.39.95 I 



soft. 

s .98 



500 1,000 11,000 
S9. S15. J105. 



VISA 



(213)679-9001 



Circle 204 on inquiry card. 



All merchandise sold by California Digital is premium grade. 
Sorry, no COD's. Orders are shipped the same day received. 
California residents add 6%. Foreign orders add 10%. 
Orders over $25, when accompanied by payment, are shipped 
at our expense. Otherwise, please add $2. 



BYTE February 1980 239 



FLOPPY SYSTEMS 




8" Siemens FDD120-8D 

AM Siemens options in- 
cluded in this drive 
may be configured hard 
or soft and single or 
double density. We find 
this to be an extremely 
reliable drive. $430.00 
Fully Shugart compatible. 
SV" BASF Magical Miniature Mini 
drive only 2/3 the size of others 
is reliable and durable and quickly 
gaining in popularity with our 
customers. Single or dual density 
fast access times $259.00 

Tarbell Controller may be re- 
configured to control 5V drives 
and includes short cable for one 
drive. KIT $179.00, ASM $265, 
but only$219 with purch. of 2 drives. 

Cable Kits For 8" Drives with 
10' 50 cond. cable and conn 
i> ectors. Also power cable and 
HP connectors. Flat cable assem 

if you wish. For one drive 
27.50, two 33.95, three 38.95 



Cable Kits for 5V«" Drives as above, but 34 
cond. For one drive 24.95, two 29.95. 





SOFT- 
WARE: 
SUPERDOS I (Z-80) 
Single User, UNIX -Like 
File System, AND Totally 
Upward Compatable From "XX/X" 
(What did you say, Digital Research??) 

PS: SUPERDOS -I runs on the TRS-80, 
and can transform it from a toy computer 
to a real business machine !!! 



10MBy 
DRIVE 
$3300 

S- 100 

DMA 

CONTROL 



POWER 

UNIT 
$395.00 



For the first time in something like 10 years, 
a new STANDARD in removable media has 
evolved. Selected by Datapoint, and others 
who have not yet announced, this drive is 
beautifully simple and easy, if not trivial to 
maintain. 920kBy/sec. transfer rate, 3600 RPM 
39 lbs and only 125 Watts. 





32K- $490.00 16K 



"Power One" Model CP206 
Power Supply adequate for 
at least two drives. 2.8A/24V 
2.5A/5V, 0.5A/-5V beautiful 
quality. $99.00 



CABINETS for FDD120and 
801 B drives, or CP206 supply. 
Matte finish in mar resistant 
black epoxy paint and stack- 
ing design 29.95 



DISKETTES 

(3M, MRX, BASF, 
Georgia Magnetics, 
& Victor Borge) 
8" $39.95/10 
5%" $29.95/10 
$290.00 



NEW!! - CHRISLIN 64K Dynamic RAM $750.00 
(Showing Amazing Similarity to TarbeM's unit) 
(16K Shown in photo) 



.,_,,. ...... . - 


|pg||ffpffy 



32K-$549.00 16K-$349.00 

"BACK TO SCHOOL" 
KEYBOARD SPECIAL 



CHERRY "PRO" Keyboard $119.00 
Streamlined Custom Enclosure $34.95 
BOTH ONLY $124.95 !!!!!!!! 




Elect rolabs 

POB 6721, Stanford, CA 94305 

415-321-5601 800-227-8266 

Telex: 345567 (Electrolab Pla) 
Visa MC Am. Exp. 



Daisy Wheel Printers 
|H Qume Sprint 3\45 

PRINTER (factory warr.) $1199.00 
POWER SUPPLY (Boschert) $349.00 
(shown mounted on rear of printer) 

COMBINATION SPECIAL $1699.00 

DATA DISPLAY MONITORS 

Used 12" Sylvania mon- 
itors. Composite Video, 
15 MHz, 120V AC. Re- 
built with NEW P39 
anti-glare tube $119.00 
New P4, 109.00, used 
P4 79.00. 
U-fix model, 10/$300.00 






New! 



ESAT 200B 



BILINGUAL 80x24 

COMMUNICATING 

TERMINAL 

Scrolling, full cursor, bell, 
8x8 matrix, 110- 19,200 
baud, Dual Font Appli- 
cations. Arabic & Hebrew, 
Multilingual Data Entry 
Forms Drawing, Music, & 
Switchyards. $349.00 



»gf«f mim m wit m i\ 



£ ^isv <, *' ,iw:t * 



OEM STYLE" as above, 
will fit any case. (Both 
versions serviced by quali- 
fied tech). Identical to 
above but subtract $12.00 

Doppler Motion Sensor 
Intrusion Detector 

Extremely effective microwave 
motion detector for detecting 
unwanted visitors. Ignores mice 
and other non-larcenous creatures. 
Operates on 12VDC or from small 
transformer supplied. Output is 
relay closure for alarm control 
interface, or to switch on lights 
annunciators. Will operate THROUGH 
door of closet or thin wall. Best 
application seems to be to turn 
on outside lights to help invited 
guests, and to intimidate un- 
wanted ones. $159.00 
Water Repellent Cover S24.95 



SOCKET SPECIAL 




"Won't Let Go" 

Low Profile 
Solder Tail 
1 CENT/ Pin!! (0.75/1000's) 

8 14 16 18 20 22 24 28 40 



240 BYTE February 19B0 



CP/M* Source Code --FREE! when you purchase "OS-1" 
Electrolabs' new operating system for the Z-80 designed to have exactly 
the appearance of UNIX**, including virtual I/O, "set TTY", a tree and a 
shell, filters and pipes PLUS total compatability with CP/M software! 

^^% ^^k ^fl © (Because OS-1 is truly a comprehensive 

I I ^^ "OS", and not merely a file handling 

I B ^ "i I ccatiidtc "DOS", we have changed the name 

^J \J I rtrtlUHtb from "Superdos" to "OS-1") 

VIRTUAL I/O - copy with a single command between floppy and hard 

disk, or from TTY to printer to tape to disk... etc., etc. 

No messy I/O routines to write, & no awkward transfers. 
SECURITY - 9 modes of file protection, user and login protection. 
MULTI-USER - up to 256 passwords, (non-simultaneous users) 
16MBy FILE SIZE - but no limit to no. of directories per device, thus 

allowing EASY implementation of gigantic storage devices. 
"SET TTY" - for printer or crt: tabs, page width, buffer, cursor, UC/LC, 

fonts, formfeed, arbitrary control characters etc., etc. 
"LOGIN" - automatically executes user selected programs and "set TTY". 
OCCUPIES 12KBy - only 50% larger than CP/M, but 500% more features. 
CP/M & CDOS COMPATABLE - your library is guaranteed to run! 

* (Naturally, we are not giving away the version of CP/M written by 
Digital Research, Please pardon our pun, but they might object. 
What we ARE giving you is a greatly enhanced version of CP/M 
which resides on OS-1, and allows the user of OS-1 to run any and 
all of his programs, packages or system utilities which are already 
running on CP/M. We give you the source code at no charge so 
that you may modify any part of the CP/M to suit your own sys- 
tem requirements. At no charge, you also receive the enhancement 
allowing 4MBy files instead of 256K.) 

OS-1 (with debugger, linker and screen oriented editor $199.00 

Update service, per year 29.00 

Symbolic Debugger 1 50.00 

MACRQ-Assembler (Creates relocatable code) 1 50.00 

"C" Compiler 660.00 

FORTRAN Compiler 100.00 

BASIC Compiler (very fast) 350.00 




PAPER TIGER 

IDS MODEL 440 

— 8 Software Selectable Character 
Sizes 

— Parallel & Serial Interface 

— 98 ASCII Character set, upper 
& Lower case 

— Forms length control 

— Tractor Feed $995.00 
Graphics option with 2K CRT 

screen buffer add $199.00 



DYNAMIC DEVICES MODEM 




— Acoustically coupled modem 




assembly set /> r i. 




- Asynchrous 0-300 Baud jf| 




— Switchable originate or answer 




modes ^~ ,. 




— Operates full or half duplex ; HC"1B 


■i^I_"~- — -^.. Wt 


mode ^^|W 




— 15 minute assembly $149.95 





NEW YEAR'S IC 
(While Supply Lasts) 

MEMORY &EPR0M 

2114- $ 3.00 

2114-2 6.99 

Pd41 1 2.50 

2107 (pull outs) 2.00 



SPECTACULAR 



7001 (pull outs) 2.00 


4116 (set of 8, 


16K) 




69.00 


5204 


4.95 


2708 


8.95 


2516 


35.00 


2716 


35.00 



ELECTROLABS 
POB6721 Stanford, CA 94305 
415-321-5601 800-227-8266 
Telex: 345567 (Electrolab Pla) 



TMS2716 


19.00 


2732 


95.00 


CPU 




1802CD 


$19.95 


6502 


6.25 


Z-80 


9.95 


Z-80A 


12.95 


8080A 


8.99 


8085 


2Z00 


8741 


79.00 



FLOPPY CONTROLLERS 

1771 $26.95 

1791 37.95 

Pd372 39.00 

MISCELLANEOUS (CALLUS!!) 




Graphics 

High Resolution ' 480x512 

for B&W and Color Imaging and Graphics 

ght pen, A-D, D-A, TV synchro (needs no time base 
correction or adjustment with anything between ran- 
dom interface & NTSC commercial standard). T.V. 
single frame grabber ("snapshot"). Up to 1 Byte of at- 
tributions per pixel. 



LSI-100&S-100 applied to: 

Graphic Presentation — such as computer generated animation Si other 
graphic displays up to 256 colors & up to 256 b&w gray scales. Image 
Analysis - using built-in FRAME GRABBER, for medical image en- 
hancement, contour analysis, & pattern recognition. Commercial TV 

Tilting & Advertising — using synchronization capability. Interactive 

graphics — using light pen accessory. 

BASIC CONFIGURATION - 

LSI-11$1995. S-100$1265. 
For TRS-8D/Exidy Add $595.00 
Includes: Data Board - 32K (480 
x 512 x 1 pixel) D-A 16 level video 
generator. Video Synchronization 
Circuitry. Address Control & Tim- 
ing Board. 

FEATURES - High speed. DMA 
or 2KBy window memory mapped interface. 
Full NTSC commercial color capability. Low 
power consumption. Excellent Software 

Options - Accessories - Software 

Options include: light pen, auxilliary outputs, 
text mode, memory and much more. Acces- 
sories include: b&w and color cameras and 
monitors. Software: "Plot" 2D or 3D, 
"Tilting", "Contour", "Image Enhance- 
ment", "Vector Curve Generation". 

Call for price and details 

•CPM and "UNIX 

trademarks of Digital Research and Western Electric respectively 

Circle 206 on inquiry card. 




BYTE February 1980 241 



MATCHMAKER TECHNOLOGY 

TURNKEY DISK SUBSYSTEMS 

DISK 



IS 



IN!!! 



For those who wish to avoid the 
aggravation, fussing, irritation, an- 
noyance etc., of assembling your 
own subsystem, plug in and GO!!! 




^SORCERER 
sTRS-80 
tsAPPLE 

1 ^ HPIB 
sPET 



APPLE 



SORCERER 



FEATURES: 

— 2 8" Floppy DISK DRIVES (Single Sided) 

— Color Coordinated Cabinet with Power Supply 

— Expanded version of APPLE-DOS 

— Single Density Disk Controller 

— Full Cabling, Connectors + Documentation 

— Assembled and Tested 

-Plug In and GO!!! $1695.00 

OPTIONS: 

— 2 8" Double Sided Drives (In place of Single Sided) 

$2395.00 

— 16K Internal Memory Expansion Kit 69.00 



PET 



Prices and specifications same as for APPLE except 
PET Operates via PET-DOS 



TRS-80 



Prices and specifications same as for SORCERER with 
following exceptions: 

— Expansion Interface necessary 

— Space for up to 48K plug-in dynamic memory on 
Controller Card 

— Software package as above $ 995.00 



FEATURES: 

— 2 8" Single Sided Floppy Disk Drives 

— Single and/or Double Density 

— Color Coordinated Cabinet with Power Supply 

— Full RS-232 Interface 

— OS-1 Disk Operating System (Fully CP/M 

Compatible) CP/M is a registered trademark of Digital Research 

— Full Cabling, Connectors + Documentation 

— Assembled and Tested 

— One S-100 Slot available for Memory Expansion 
-Plug In and GO!!! $2195.00 



OPTIONS: 

- 2 8" Double Sided Drives (In place of Single Sided) 

$2845.00 

- 32K Dynamic RAM Memory Board, Assembled 
and Tested $ 299.00 

- 16K Dynamic RAM Internal Memory Expansion Kit 

$ 69.00 

- Deluxe Business Software package includes: 
C BASIC 

WORD PROCESSING SOFTWARE 
INTERACTIVE "Big 4": 

General Ledger, Accts. Payable, Accts. Rec. 

and Payroll $ 695.00 

- 10 MBY Removeable Hard Disk - Call for Details 



ANOTHER Fine Product brought to you exclusively by the folks at: 



In California: 415-321-5601 
Outside Cal: 800-227-8266 



Electrolabs 



Worldwide: 

TLX: 345567 Electrolabs PLA 



FOB 6721, Stanford, Ca. 94305 



242 BYTE February 1980 




MICROLEASE! 

A unique nationwide leasing 
program designed to facilitate 
the purchase and sale of com- 
puters and peripherals. 

Whether you are buying or sell- 
ing, MICROLEASE is your best 
leasing choice. 

Excellent Rates. Fast Service 
by Computer Professionals. 

EVERGREEN 

22 Concord Avenue 

Cambridge, MA 02138 

(617)868-3425 



16 K RAMS & RAM CONTROLLERS 

16 K X 1 DYNAMIC RAMS mimii6P3 

• 200 NSEC ACCESS/375 NSEC CYCLE TIMES 

• 16PIN/TTL COMPATIBLE 

• ALL CHIPS BURIED IN AND FULLY TESTED 

• PRICE WITH DATA SHEET 

S66.00 IN OTY OF 8/THAT'S 58.50 EACH 

6800/6502 64K BYTE RAM & CONTROLLER SET 
MAKE 64 K BYTE MEMORY FOR YOUR 6800 OR 6502 
THIS SET INCLUDES 

• 32 M5K 4116-3. 16K X |, 200 NSEC RAMS 

• 1 MC3480 MEMORY CONTROLLER 

• 1 MC3242A MEMORY ADDRESS MULTIPLEXER 
AND COUNTER 

• DATA & APPLICATION SHEETS PARTS TESTED 
AND GUARANTEED. 

S295.00 PER SET 

DYNAMIC MEMORY CONTROLLER MC3480L 

• GENERATES RAS/CAS & REFRESH TIMING FOR 
16K TO 64K BYTE MEMORIES 

. PRICE WITH OATE SHEET S13.95 EACH 

MEMORY ADDRESS MUX/COUNTER mc3W?ap 

• MUX ADDRESS S REFRESH COUNTER FOR 16K TO 
G4K BYTE MEMORIES 

• PRICE WITH DATA SHEET S12.50 EACH 

OUANTUY DISCOUNTS AVAILABLE 
All ORDERS POSTPAID US FUNDS 0% IN TERNfl TID'JJ".! 

ORDERS CHEEK Dfl M0NEV ORDER VISA18A.MC AIS0 AC 
CEP1EC SEWJAl'CT NO EXPIRATION DATE &INTEB8ANK 
NO WITH SIGNED ORDER CALIF RESIDENTS PLEASE ADO 
(iS SAIES TAX PHCJE OflOtHS 1/IJ1 633 4460 

MEASUREMENT SYSTEMS & CONTROLS, inc 

MEW0R1 DEVICES DIVISION 
66/ NORTH MAIN ST .. ORANGE CA 92BfiB 



Circle 208 on inquiry card. 



Circle 209 on inquiry card. 



Circle 210 on inquiry card. 




APPLE DOS COMPATIBLE 

• DOUBLES APPLE ] I" STORAGE 

• SHUGART 800/801 COMPATIBLE 

• STANDARD IBM" 3740 FORMAT 

• CP/fvTUCSD PASCAL"" CAPABILITY 

Available at your local APPLE Dealer: $400. 



SORRENTO VALLEY ASSOCIATES 



Circle 211 on inquiry card. 



TRS-80, PET, 
APPLE, 

SORCERER 

Hardware/Software 
Systems 



Available Now: 

MHAM INTERFACE - including 
the most sophisticated RTTY 
systems money can buy. 
UBaudot and ASCII printer inter- 
faces. 

MEIectra Sketch- .ANIMATION 
GRAPHICS Compiler. 

Write or tall far free catalog 

/VMCROTRONICS, inc. 

1125 N. Golden State Blvd. 
Suite G (A) Turlock, CA. 95380 
(209) 634-8888/667-2888 

We are experiencing telephone difficulties, 
please keep trying. 



FLOPPY DISK 
REPAIR 

I | t?i::?;#''";": ,|, T't , '*vi;:"*Tii! : ?i::::;<ii 1 ':' 

I':'.- VI " ■■'■■ '"I '■' " <<' 

• PerSci, Shugcirt 
Apple 

• Quick Turnaround 

• Reasonable prices 

yi.^tZrrf'j^r'i^iivi;::::::::::^!;::!::;:::::^*,;, 

Computer Service Center 

1023 N. LaBrea 

Hollywood, CA 90038 

213-851-2226 



Circle 212 on inquiry card. 



HOW CAN I GROW 
B TREES? 

ORDER MICRO B +™ 

• Get fast insertion, retrieval 
and deletion of index entries. 

• Never need to reorganize 
your index; no matter how 
often it is updated. 

MICRO B+ SOURCE CODE $195 
MICRO B + DEMO DISK $25 

SHIPPING $2 USA. $5 FOREIGN 

Available in 8" format lor CBASIC-II 

and MICROSOFT Basic Version 5. 



314-445-3304 
Check/ VISA/ Mastercharge 




SPRINT 68 
MICROCOMPUTER 

CONTROL COMPUTER 
DEVELOPMENT SYSTEM 

6800 MPU, serial I/O, 48K RAM, dual 8" 
drives, WIZRD multitasking DOS, 
Editor, Assembler, 12K BASIC all for 
$3995. 

SOFTWARE OPTIONS 

C compiler, PL/W compiler, PASCAL 

HARDWARE OPTIONS 

EROM Programmer, analog I/O, parallel 
I/O, 488 GPIB 



WIN! hi: 



Corp 



1801 South Street 
Lafayette, IN 47904 
Phone: (317) 742-8428 



Circle 213 on inquiry card. 







CASSETTE 
DUPLICATION 


TRS-80 (I & II), PET, APPLE, KIM, ATARI 

Quality software duplication is more 
than copying cassettes. Microsette du- 
plication uses a proprietary high speed 
duplicator designed specifically for 
computer program duplication. The fin- 
ished products are of consistent quality, 
guaranteed to load. Minimum order is 
100 with discounts for higher quanti- 
ties. Call (415) 968-1604 for details. 


1 


» 


l ». 


Mffl»t| 


S • ■■ • 4! 


1 = • mt m » 








MICF 

475 

Mt.Vi 


OSETTE CO. 
Ellis Street 
ew, CA 94043 



Circle 214 on inquiry card. 



Circle 215 on inquiry card. 



Circle 216 on inquiry card. 



C04000 
CD4001 
CD40G2 
CD4Q06 
CD4007 
CMOQS 
CD4010 
CD4011 
CD40I2 
CD4013 
CD4014 
CO401S 
CD4016 
CD4017 
CD40I8 
CD4019 
CD4020 
CD4021 
CD4022 
CD4023 
CD4024 
CD4025 
CD4026 
CD4027 



74COO 
74C02 
74C04 
74C08 
74C1D 
74C14 
74C20 
74C30 
74C42 
74C48 
74C73 
74C74 



78MG 

LM106H 

LM300H 

LM301CN/H 

LM3Q2H 

LM304H 

LU305H 

LM307CN/H 

LM308CN/H 

LM309H 

LM309K 

LM310CN 

LM311N/H 

LM312H 

LM317K 

LM318CN/H 

LM319N 

LM320K-5 

LM320K-5.2 

LM320K-12 

LM320K-15 

LM320K-18 

LM320K-24 

LM320T-5 

LM320T-5.2 

LM320T-B 

LM320T-12 

IM320T-15 

LM320T-1B 

LM320T-24 

LM323K-5 

LM324N 

LM339N 

LM340K-5 

LM340K-5 

LM340K-8 

LM340K-12 

LM340K-15 



74LS00 
74LS01 
74LS02 
74LS03 
74LS04 
74LS05 
74LSOB 
74LS09 
74LS10 
74LS11 
74LS13 
74LS14 
74LS15 
74LS20 
74LS21 
74LS22 
74LS26 
74LS27 
74LS28 
74LS30 
74LS32 
74LS37 
74LS40 
74LS42 



7400 TTL 



SN7470N 
SN7472N 
SN7473N 
5N7474N 
SN747SN 
SN7476N 
SN7479N 
SN74S0N 
SN74B2N 
SN7483N 
SN74B5N 
SN7486N 
SN74B9N 
SN7490N 
SN7491N 
SN7492N 
SN7493N 
SN7494N 
SN7495N 
SN7496N 
SN7497N 
SN7410ON 
SN74107N 
SN74109N 
SN74116N 
SN74121N 
SN74122N 
SN74123N 
SN7412SN 
SN74126N 
SN74132N 
SN74136N 
SN74141N 
SN74142N 
SN74143N 
SN74144N 
SN74145N 
5N74147N 
SN74148N 
SN74150N 
SN74151N 
SN74152N 
SN74153N 
SN74154N 
SN74155N 
SN74156N 
SN74157N 



2.95 
2.95 

? 9S 



C/MOS 



CTJ4028 
CD4029 
CO4O30 
CO4035 
CD4040 
CD4041 
CD4042 
CD4043 
CD4044 
CD4046 
CD4047 
CD4048 
CD4049 
CD4050 
CD4051 
CO40S3 
CD4056 
CD4059 
CD4Q60 
CD40E6 
CD4068 
CO40G9 



74C00 



74C85 
74C90 
74C93 
74C95 
74C107 
74C1S1 
74tl54 
74C157 
74C160 
74C161 



LINEAR 

LM340K-18 1.35 

LM340K-24 1.35 

LM340T-5 1.25 

LM340T-6 1.25 

LM340T-8 1.25 

LM340T-12 1.25 

LM340T-15 1,25 

LM340T-18 1.25 

LH340T-24 1.25 
LM358N 



LM370N 

LM373N 

LM377N 

LM380N 

LM380CN 

LM3B1N 

LM3B2N 

NE501N 

NE510A 

NE529A 

NEsaiHAf 

NE536T 

NE540L 

NE544N 

NE55DN 

NE555V 

NE556N 

NE560B 

NE562B 

NE565N/H 

NE566CN 

NE567V/H 

NE570N 

LM703CN/H 

LM709N/H 



1.95 
3.25 



74LS00TTL 



74LS47 
74LS51 
74LS54 
74LS55 
74LS73 
74LS74 
741S75 
74LS76 
74LS78 
74LS83 
74LS85 
74LS86 
74LS90 
74LS92 
74LS93 
74LS9S 
74LS96 
74LS107 
74LS109 
74LS112 
74LS123 
74LS125 
74LS132 
74LS136 



^W 



SN74160N 
SN74161N 
SN74162N 
SN74163N 
SN74164N 
SN74165N 
SN74166N 
SN74167N 
SN74170N 
SN74172N 
SN74173N 
SN74I74N 
SN74175N 
SN74176N 
SN74177N 
SN74179N 
SN741B0N 
SN741B1N 
SN741B2N 
SN74I84N 
5N74185N 
SN74186N 
SN741B8N 
SN74190N 
SN74191N 
SN74192N 
SN74193N 
SN74194N 
SN74195N 
SN74196N 
SN74197N 
SN74198N 
SN74199N 
SN74S200 
SN74251N 
SN74279N 
SN742B3N 
SN74284N 
SN74285N 
SN74365N 
SN74366N 
SN74367N 
SN74368N 
SN74390N 
SN74393N 



CD407O 

CD4071 

CD4072 

CD4Q76 

CD4081 

CO40B2 

CD4093 

CO4098 

MCI 4409 

MCI4410 

MC14411 

MC14419 

MC14433 

MCI 4506 

MC14507 

MC14562 

MC145B3 

CD4508 

C045I0 

CD4511 

CD4515 

CD4518 

CD4520 

CD4566 



74C163 
74C164 
74C173 
74C192 
74C193 
74C195 
74C922 
74C923 
74C925 
74C926 
80C95 
80C97 



1 50 



LM710N .79 

LM711N .39 

LM723N/H .55 

LM733N 1.00 

LM739N 1.19 

LM741CWH .35 

LM74M4N .39 

LM747N/H .79 

LM748N/H .39 

LM1310N 1.95 

LM1458CN/H .59 

MC1488N 1.95 

MC1489N 1.95 

LM1496N .95 

LM1556V 1.75 

MC1741SCP 3.00 

LM2111N 1.95 

LM2901N 2.95 

LM3053N 1.50 

LM3Q65N 1.49 
LM3900N(3401).59 

LM3905N 1.48 

LM3909N 1.25 

MC5558V .59 



LM75450N 

75451CN 

75452CN 

75453CN 

75454CN 

75491CN 

75492CN 

75493N 

75494CN 

RC4136 

RC4151 

RC4194 

RC4195 



■155 



74LS138 
74LS139 
74LS151 
74 LSI 55 
74LS157 
74LS160 
74LS161 
74LS162 
74LS163 
74LS164 
74LS175 
74LS1B1 
74LS190 
74LS191 
74 LSI 92 
74LS193 
74LS194 
74LS195 
74LS253 
74LS257 
74LS258 
74LS260 
74LS279 
74LS367 
74LS3BB 
74LS670 



aCromemco 
Incorporal ed 





mom 



Cromamco's 8K BYTESAVER® card provides 
a built-in programmer for the popular 2708 
PROM and has the capacity for a full i! K bytes of 
PROM memory storage. Tho BYTESAVER® II 
also offers a number of new features including 
convenient switch selection of board address 
and Cromemco's powerful memory bank 
selection. The BYTESAVER® II is assembled 
and tasted (Model 8KBS-W) for $245. 



8K 
Bytcsaverll 

Memory Capacity: 8K bytes 

Memory Type: 2708 PROM or equivalent 

Memory Access Time: 450 nanoseconds 

Wait States at 2MHz: none required 

Wait States at 4MHz: one per machine cycle 

Bus: S-1O0 

Power Requirements: +8V @ 0.8A 
+18V@0.4A 
-1 8V 9 0.2A 

Operating Environment: 0-55°C. 

Assembled 

8KBS-W... $245.00 



DISCRETE LEDS 





ZOO" ma. 


XC556R 


red 


XC556G 


green 


XC556Y 


yellow 


XC556C 


clear 




.200- die. 


XC22R 


red 


XC22G 


green 


XC22Y 


yellow 




170" die. 


MV10B 


red 




085 die. 


MV50 


red 


INFRA-RED 


1/4-K1/4M/16 




5/S1 



5/11 




125- die. 




4/S1 


XC209R 


red 


5/{1 


4/$f 


XC209G 


green 


4/J1 


4/$1 


XC209Y 


yellow 


4/S1 


5/S1 
Ml 

4/11 




IBS" die. 




XC526R 


red 


MSI 


XC526G 


green 


4/S1 


XC526V 


yellow 


«Si 


4/S1 


XC52GC 


clear 


4/S1 




190 dla. 




6/J1 
LED 


XC111R 


red 


SSI 


XC111G 


green 


m 


XC111V 


yellow 


4/S1 




XC111C 


clear 


4/S1 



TIMEXT1001 

LIQUID CRYSTAL DISPLAY 
CLASS II 

FIELD EFFECT 




4 DIGIT- 5" CHARACTERS 
THREE ENUNCIATORS 
2.00" X 1.20" PACKAGE 
INCLUDES CONNECTOH 

TIOOI-Transmiwive $7.95 

TirJ01A<Reflectiue B.25 



DISPLAY LEDS 



TYPE 
MAN 1 
MAN 2 
MAN 3 
MAN 4 
MAN7G 
MAN 7Y 
MAN 72 
MAW 74 
MAN 82 
MAN 84 
MAN 3620 
MAN 3630 
MAN 3B40 
MAN 4610 
MAN 4640 
MAN 4710 
MAN 4730 
MAN 4740 
MAN 4810 
MAN 4840 
MAN 6610 
MAN 6630 
MAN 6640 
MAN 6650 
MAN 6660 
MAN 66BO 
MAN 6710 



POLARITY I 

Common An ode -red 
5 x 7 Dal Matrix-red 
Common Cathode-red 
Common Cathode-red 
Common Anode 'green 
Common Anode-yellow 
Common Anode-red 
Common Cathode-red 
Common Anode-yellow 
Common Cathode -ye I low 
Common Anode-oranoe 
Common Anodo-oranrjo ± 1 
Common Cathode -orange 
Common Anode-oranne 
Common Cathode -orange 
Common Anodo-rert . 

Common Anode-red & 1 
Common Cathode -red 
Common A node -yellow 
Common Calhode-yellaw 
Common Anode-orange-D-D 
Common Anode-orange ± 1 
Common Caihode-orango-O.O. . 
Common Cathode-orange * 1 . 
Common Anode-orange 
Common Cathode -orange 
Common Anode-ied-D.D 



TYPE 

MAN 6730 

MAN 6740 

MAN 6750 

MAN 6760 

MAN 6780 

DL70t 

DL704 

DL707 

DL72B 

OL741 

DL746 

DL747 

OL749 

0L750 

DL33B 

FND70 

FN035B 

FND359 

FNDS03 

FN0507 

5082-7730 

HDSP-3400 

HDSP-3403 

5082-7300 

5083-7302 

50B2-7304 

5082-7340 



POLARITY 

Common Anode-red * 1 
Common Cathode -refl-D.D. 
Common Cathode-red s 1 
Common Anode-red 
Common Cathode -red 
Common Anode-ted = 1 
Common Cathodo-red 
Common Anode-red 
Common Ca!hode-red 
Common Anode -red 
Common Anode'red = 1 
Common Anode-red 
Common Cathode-red t 1 
Common Cathode -red 
Common Cathode-red 
Common Cathode 
Common Cathode ± 1 
Common Cathode 
Common Cathode) FN D500) 
Common Anode (FND510) 
Common Anode-red 
Common Anode-red 
Common Cathode red 
4x7 sgl. Digit-RHDP 
4 x 7 Sgl. Digit-LHDP 
Overrange character (±1) 
4x7 Sgl. Digit -Hexadecimal 



19.95 
15.00 
22.50 



RCA LINEAR 



CA3013T 
CA2023T 
CA3035T 
CA3039T 
CA3046N 
CA3059N 
CA3060N 
CA30B0T 
CA3081N 



2.15 CA3082N 

2.56 CA30B3N 

2.48 CA3086N 

1.35 CA30B9N 

1.30 CA3130T 

3.25 CA3140T 

3.25 CA3160T 

.85 CA3401N 

2.00 CA3600N 



CALCULATOR 
CHIPS/DRIVERS 

MMS725 S2.95 

MM5738 2.95 

DM8864 2 .00 

DM8S65 100 
DMB887 .75 

DM8889 .75 

9374 7 seg. 
C.A. LEO d 



CLOCK CHIPS 


MOTOROL/ 




MM5309 


S4.95 


MC1408L7 


M SS 


MM5311 


4.95 


MC1408LB 


S75 


MM5312 


4.95 


MCI439L 


9M 


MM5314 


4.95 


MC3022P 


?95 


MM5316 


6.95 


MC3061P 


3.50 


MMS318 


9.95 


MC4016(74416) 


1 Mt 


MM5369 


2.95 


MC4024P 


3.95 


MM5387/1998A 


4.95 


MC4040P 


H.95 


CT700I 


695 


MC4044P 


4.50 



B pin LP 
14 pin LP 
16 pin LP 
18 pin LP 
20 pin LP 



24 pin ST 
8 pin SG 
14 pin SG 
16 pin SG 
18 pin SG 

Spin WW 
10 pin WW 
14 pin WW 
16 pin WW 
18 pin WW 
20 Din WW 



IC SOLDERTAIL — LOW PROFILE (TIN) SOCKETS 
49 50-100 1-24 

22 pin LP S .37 

24 pin LP .38 

28 pin LP .45 

.27 36 pin LP 60 

30 SOLDERTAIL STANDARD (TIN) 40 P' n LF w 

2B pin ST S .99 
36 pin ST 1.39 
40 pin ST 1.59 

SOLDERTAIL STANDARD (GOLD) 

24 pin SG S .70 
?BplnSG '10 
36 pin SG 1-6S 



25-49 50-100 



WIRE WRAP SOCKETS 
(GOLD) LEVEL #3 



22 pin WW S .95 
24 pin WW 1.05 
2BplnWW 1.40 
36 pin WW 1.59 
40 pin WW 1.75 



10 OHM 12 OHM 

27 OHM 33 OHM 

6B OHM 82 OHM 

1B0 OHM 220 OHM 770 OHM 330 OHM 390 OHM 

470 OHM 560 OHM 680 OHM 8?0 OHM IK 



15 OHM 
39 OHM 
100 OHM 



18 OHM 
J 7 OHM 
120 OHM 



50 OHM 



50 PCS 
50 PCS 



1/4 WATT RESISTOR ASSORTMENTS - 5% 

$1.75 
1.75 
1 .75 
1.75 
1.75 
1.75 

1.75 

ASST. 8R Includes Resistor Assortments 1-7 (350 PCS.) $9.95 ea. 



1.?K 

3.3K 



1,-SK 

3.9K 



J 70K 
1.2M 
3.3M 



2.2K 
5.SK 



2.7K 
6.8K 



S10.00 Min. Order - U.S. Funds Only Spec Sheets — 254 

Calif. Residents Add 6% Sales Tax 1980 Catalog Available -Send 41 d stamp 

Postage — Add 5% plus$1 Insurance (if desired) 

PHONE 

ORDERS 

WELCOME 

(415) 592-8097 




ameco 



ELECTRONICS 



MAIL ORDER ELECTRONICS - WORLDWIDE 

1355SHOREWAY ROAD, BELMONT, CA 94002 

ADVERTISED PRICES GOOD THRU FEBRUARY 



TELEPHONE/KEYBOARD CHIPS 

AY-5-9100 Push Button Telephone Dialler 

AY-5-9200 Repertory Dialler 

AY-5-95O0 CMOS Clock Generator 

AY-5-2376 Keyboard Encoder (68 keys) 

HD0165 Keyboard Encoder (16 keys) 

74C922 Keyboard Encoder (16 keys) 

74C923 Keyboard Encoder (20 keys) 



SM.«\ 

14.95 
4.95 

14.95 
7.95 
7.95 
6.25 





ICM CHIPS 




ICM7045 


CMOS Precision Timer 


24.95 


ICM7205 


CMOS LED Stopwatchmmer 


19.95 


ICM7207 


Oscillator Controller 


7.50 


ICM7208 


Seven Decade Coonler 


19.95 


ICM7209 


Clock Generator 


6.95 



NMOS READ ONLY MEMORIES 

MCM6571 128 X9X 7 ASCII Shifted with Greek 13.50 

MCM6574 128 X 9 X 7 Math Svmbol & Pictures 13.50 

MCM6575 128 X 9 X 7 Aloha 1 Control Char Gen 13.50 



TL074CN 

TL494CN 

TL496CP 

I1C90 

951190 

4N33 

MK50240 

OS0026CH 

TIL308 

MM5320 

MM5330 

LD110/111 

MC14433P 



MISCELLANEOUS 

Quad Low Noise bi-fet Op Amp 
Switching Iteijulator 
Single Switching Regulator 
Divide 10/11 PrescaTer 
Hi-Speed Divide 10/11 Prescaler 



2.49 
4.49 
1.75 
19.95 
11.95 
3.95 
17.50 
3.75 
.27" red num. display w/integ. logic chip 10.95 
TV Camera Sync. Generator 14.95 

4'/z Digit DPM Logic Block (Special! 3.95 

3Vi Digit A/D Converter Set 25.00/set 

3v* Digit A/D Converter 13 95 



Photo-Darlington Opto-lsolator 
Top Octave Freq. Generator 
5Mhz 2-phase MOS clock driver 



LITRONIX ISO-LIT 1 

Photo Transistor Opto-lsolator 
ISame as MCT 2 or 4N25) 

49i< each 



SN 76477 

SOUND GENERATOR 
Generates Complex Sounds 
Low Power - Programmable 

$3.95 each 



TV GAME CHIP AND CRYSTAL 

AY-3-8500-1 and 2.01 MHZ Crystal (Chip & Crystal - n _ . . 

includes score display. 6 games and select angles etc. 7.95 /SBt 



$8.40 
4.40 
4.40 
1.55 
1.50 
.39 



XR205 
XR210 
XR215 
XR320 
XR-L555 
XR555 
XR556 
XR567CP .99 
XR567CT 1.25 
XR1310P 1.95 
XR1468CN 3.85 
XRI488 1.95 
XR1489 1.95 



EXAR 



JE2206KB 19.95 

XR1800 3.20 

XR2206 4.40 

XR2207 3.85 

XRZ208 5.20 

XR2209 1.75 

XR2211 5.25 

XR2212 4.35 

XR2240 3.45 



XR2242CP 1.50 
XR2264 4.25 



XR2556 
XR2567 
XR3403 
XR4136 
XR4151 
XR4194 
XR4202 
XR4212 
XR4558 
XR4739 
XR4741 



3.20 
2.99 
1.25 
1.25 
395 
4 95 
3.60 
2.05 



TYPE 

1N746 

1N751 

1N752 

1N753 

1N754 

1N757 

1N759 

1N959 

1N965 

1N5232 

1N5234 

1N5235 

1N5236 

1N5242 

1N5245 

1N456 

1N458 

1N4B5A 

1N4001 



DIODES 

VOLTS W 

3.3 400m 

5.1 400m 

5.6 400m 



2,0 400m 

12.0 400m 

8.2 400m 

15 400m 

5.6 500m 

6.2 500m 

6.8 500m 

7,5 500m 

12 500m 

15 500m 



4/1,00 
4/1,00 
4/1.00 
4/1.00 
4/1.00 
4/1.00 
4/1.00 
4/1.00 



TYPE 
1N4002 
1N4003 
1N4004 
1fJ4005 
1N4006 
1N4007 
1N3600 
1N4148 
1N4154 
1N4733 
1N4734 
1N473S 
1N4736 
1N4738 
IN4742 
1N4744 
1N1183 
1N11B4 
1N1185 
IN1 166 
1M11B8 



VOLTS W 

100 PIV 1 AMP 

200 PIV 1 AMP 
400 PIV 1 AMP 
600 PIV 1 AMP 
800 PIV 1 AMP 
1000 PIV 1 AMP 
200m 



PRICE 
12/1.00 
12/1.00 
12/1.00 
10/1.00 
10/1.C 



75 



torn 



35 10m 



12 



1w 



50 PIV 35 AMP 
100 PIV 35 AMP 
150 PIV 35 AMP 
200 PIV 35 AMP 
400 PIV 35 AMP 



SCR AND FW BRIDGE RECTIFIERS 



C36D 15A rjj 400V 

C36M 3SA(ii 600V 

2N2328 1.6AI6 300V 

MOA 980-1 I2Af« 50V 

MDA 980-3 12A<« 200V 



C106S1 

MPSA05 

MPSA06 

TIS97 

TIS9B 

40409 

40410 

40673 

2N918 

2N2219A 

2N2221A 

2N2222A 

PN2222 Plastic 

2N2369A 

MPS2369 

2N2484 

2N2906 

2N2907 

PN2907 Plastic 

2N2925 

MJE2955 

2N3053 



.50 

.30 

9/1.00 

6/1.00 
6/1 00 



1.75 

4/1,00 
2/1.00 
4/1.00 
5/1,00 
7/1.00 
4/1.00 
5/1.00 
4/1.00 
4/1.00 
5/1.00 
7/1.00 
5/1.00 
1.25 
2/1.00 



TRANSISTORS 



FW BRIDGE HEC. 
FW BRIDGE REC. 



2N305S 

MJE3055 

2N3392 

2N339B 

PN3567 

PN3568 

PN3569 

MPS3638A 

MPS3702 

2N3704 

MPS3704 

2N.3705 

MPS370S 

2N3706 

MPS3706 

2N3707 

2N3711 

2N3724A 

2N3725A 

2N3772 

2N3823 

2N3903 



5/1.00 
5/1.00 
3/1.00 
4/1.00 
4/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
5/1.00 
.65 
1.00 



2N3904 
2H3905 
W3906 
JN4013 
2N4123 
PN4249 
PN4250 
2N4400 
2N4401 
2N4402 
2N4403 
2N4409 
2N5086 
2IM5087 
2N508B 
2N50B9 
2N5129 
PN5134 
PN5138 
2N5139 
2N5210 
2N5449 
2N5951 



3/1.00 
6/1.00 
4/1.00 
4/1.00 
4/1.00 
4/1.00 
4/1.00 
4/1.00 
5/1.00 
4/1,00 
4/1.00 
4/1.00 
4/1.00 



5/1.00 

5/1.00 
3/1.00 



CAPACITOR 



LS Ifeffl Mi 



CORNER 



47 pi 

100 pl 
220 pi 
470 Dl 

.OOlmf 
.0022 
.0047ml 
.01ml 

-1/35V 

.15/35V 
22/35V 
.33/35V 
.47/35V 
.68/35V 
1.0/35V 



.47/50V 

1.0/50V 

3.3/50V 

4.7/25V 

10/25V 

10/50V 

22/25V 

22/50V 

47/25V 

47/50V 

100/25V 

100/50V 

220/25V 

220/5DV 

470/25V 

1000/I6V 

2200/1 6V 



.OOVF 
.04 .03 .0047„F 
.04 03 01j»F 
.04 ,03 022fiF 
.04 .03 047,iF 
.04 035 JjtF 
1B0 VOLT MYLAR FILM CAPACITORS 

022ml 

047ml 



.07 



,1ml 



■22ml .33 .2 

4-20*= DIPPED TANTALUMS (SOL10) CAPACITORS 
-28 .23 .17 1.5/35V m % 

.ZB .23 .17 2.2/35V % j 

.28 .23 17 3.3/25V .35 .3 

.28 .23 r 4.7/25V .33 .2 

,28 .23 .17 6.6/25V .49 .4 

.28 .23 .17 15/25V .75 .6 

.28 ,23 .17 22/6V -IS -6 

MINIATURE ALUMINUM ELECTROLYTIC CAPACITORS 



.15 



.13 



.47/25V 
.47/50V 
1.0718V 

1.0/25V 
1.0/5OV 
4.7/16V 
4.7/25V 
4.7/50V 
10/ 16V 
10/25V 
10/50V 
47/50V 
100/16V 
100/25V 
100/50V 
220/16V 
470/25V 



Radial Laid 
.15 .13 



.28 . 

V 



244 BYTE February 1980 



w* Continuity Tester and Flashlight 

Convenient versatile tool for quickly 
checking continuity of dead circuits, 
switches, appliances, cords, fuses, 
motors, control equipment, coils 
and panel boards. Also tests cir- 
cuits for low-resistance shorts and 
helps identify wires in multi-wire 
cables. Dozens of other uses. Plus 
the added convenience of a handy, 
durable flashlight. Uses two AA size 
penlight batteries (not furnished}. 
Insulated clip prevents accidental 
shorting to case. Alligator clip has 
48" lead with plug. 

RT300 *7.95 




Ssi 



MICROPROCESSOR COMPONENTS 



CONTINENTAL SPECIALTIES 



Logic Monitor 






The Logic Moni- 
tor allows you to 
check logic levels 
on all 16 pins of 
any DTL, HTL, 
TTL, or CMOS 
device. It has a typ 
ical input impedance of 
100K ohms and weighs a 
mere 3 oz. (85 grams!. It has 
an input volt, range of 4V to 15V 
and draws a max. of 100mA@10V 

LM-1 $70.00 




Willi 



Proto Clips 



ijiji 

', T 14-PIN CLIP PC-14 . . . . S 4.50 

16-PIN CLIP PC-16 . . . . S 4.75 

24-PIN CLIP PC-24 .... S10.00 

VfWt'll 40-PIN CLIP PC-40 .... $16.00 



Ptoto Boards 

PB-6 $17.95 

£JZ£3l\ PB-100 19.95 

PB-101 22.95 

W% PB - 102 26 - 95 

TVMA PB-103 44.95 

PB-104 55.95 

PB-203 99.95 

PB-203A 155.00 

PB-203A-Kit . . . 131.00 




Jumbo 6-Digit Clock Kit 

* Four .6J0"ht. and two .300"ht. 
common anode displays 

* Uses MM5314 clock chip 

* Switches for hours, minutes and hold ft 

* Hours easily viewable to 30 feet 

* Simulated walnut case 

* 115VAC operation 

* la or 24 hour operation 

* Includes all components, case and wall 

* Size: 6J/j x 3Vn x 1W 




JE747 $29.95 




■ Bright .300 ht. comm. cath- 
ode display 

• Uses MM5314 clock chip 

• Switches for hours, minutes 
and hold modes 

• Hrs. easily viewable to 20 ft. 

• Simulated walnut case 

• 115 VAC operation 

• 12 or 24 hr. operation 



JE701 

6-Digit Clock Kit $19.95 



< 3-1/8" x 1M" 



Regulated Power Supply 



Uses LM309K. Heat sink 
provided. PC board con- — 
struction. Provides a solid 
1 amp @ 5 volts. Can supply up 
to *5V, i9V and ±12V with 
JE205 Adapter. Includes compo- 
nents, hardware and instructions. 
Size: 3W x 5" x 2"H 



JE200 



$14.95 





ADAPTER BOARD 
-Adapts to JE200- 
+5V, ±9V and ±12V 



DC/DC converter with +5V input. Toriodal hi- 
speed switching XMFR. Short circuit protection. 
PC board construction. Piggy-back to JE 200 
board. Size: 354" x 2" x 9/1 6"H 



\JE205 



$12.95 



8212 
8214 
8216 
8224 
8226 
8228 
8238 
8251 
8253 
B255 
8257 
6259 



-8080A/S06QA SUPPORT DEVICES- 
CPU 

6-Bit Irput/Output 

Priority Interrupt Control 

Bi-Direflinnal Bus Driver 

Clock Generator/Driver 

Bus Driver 

System Ccntrolier/Bus Driver 

System Controller 

Prog. Comm. J/0 (USART) 

Prog. Interval Timer 

Prog. Feriph. 1/0(PPIj 

Prog. DMA Control 

Prog. Interrupt Control 
— 6800/BBDO SUPPORT DEVICES— 



S 7 95 
3.25 
5.95 
3.49 



14.95 
9.95 
19.95 
19.95 



MICROPROCESSOR MANUALS- 

M-Z80 User Manual 



-ROM'S - 



2513(2140) Cti3ractei Grieutnrl upper case) 

2513(3021) Character (Jenerator(io*er case) 

2516 Character Generator 

MM5230N 2048-Bit Real Only Memory 



MC680O MPU 

MC6802CP MPU with Clock and Ram 

MC6810AP1 128X8 Static Ram 

MC6B21 Periph. Inter. Adapt (MC6820) 

MC6828 Priority Interrupt Controller 

MC683DL8 1024X8 Bit ROM (MC68A30-8) 

MC6B50 Asynchronous Comm. Adapter 

MC6852 Synchrcnous Serial Data Adapt. 

MC6860 0-600 Dps Digital MODEM 

MC6862 2400 ops Modulator 

MC6880A Quad 3-State Bus. Trans. (MCBT26) 

MICROPROCESSOR CHIPS— MISCELLANEOUS 

Z80[7B0C) CPU | 

Z80A{780-t) CPU 

CDP1802 CPU 
MPU 



2650 
6502 
8035 



CPU 



it MPU w/clock, RAM, 1/0 lines 



TMS9900JL 16-Bit MPU vWhardware, mullipiy 

& divide 
SHIFT REGISTERS 



2101(8101) 

2102 

2IL02 

2111(8111) 

2112 

2114 

2114L 

2114-3 

21 14L-3 

5101 

5280/2107 

7489 

74S20O 

93421 

UP0414 

(MK4027) 
UP0416 

(MK4116) 
TMS4344- 

45NL 
TMS4045 
2117 



256X1 
1024X1 
256X4 
1024X1 
1024X1 
256X4 
256X4 
1024X4 
1024X4 
1024X4 
1024X4 
256X4 
4096X1 
16X4 



MM500H 

MM503H 

MM504H 

MM506H 

MM510H 

MM5016H 

2504T 

2518 

2522 

2524 

2525 

2527 

2528 

2529 

2532 

3341 

74LS670 



Dual 25 Bit Dynamic 

Dual 50 Bit Dynamic 

Dual 16 Bit Static 

Dual 100 Bit Static 

Dual 64 Bit Accumulator 

500/512 Bit Dynamic 

1024 Dynamic 

Hex 32 Bit Static 

Dual 132 Bit Static 

512 Static 

1024 Dynamic 

Dual 256 Bit Static 

Dual 250 Static 

Dual 240 Bit Static 

Quad 80 Bit Static 

Filo 

4X4 Register File (TriSlale) 



$.50 MM5262 



1702A 

2716INTEL 

TMS2516 

(2716) 

TMS2532 

2708 

2716T.I 



5203 
6301-1(7611) 1024 
6330-1(7602) 256 



- RAMS 

Static 

Dynamic 

Sialic 

Sialic 

Sialic 

Static 

Sialic M0S 

Static 450ns 

Static 450ns low power 

Static 300ns 

Static 300ns low power 

Static 

Dynamic 

Static 

Sialic Trislale 

Static 

Dynamic 16 pin 

Dynamic 16 pin 250ns 

Sialic 

1024X4 Static 
16.384X1 Dynamic 350ns 
(house marked) 
2KX1 Dynamic 

PROM'S 

2048 FAM0S 

IW EPROM 

IbK' EPROM 

"Requires single +5V power supply 
4KX8 EPROM 

8K EPROM 

16K" EPROM 

Requires 3 voltages. — 5V. +5V. +12V 
2048 FAM0S 



9.95 
14.95 



$5.95 
59.95 
4995 

8995 
10.95 
29 95 



82S23 
82S115 
82S123 



32X8 
4096 
32X6 



A-V-5-1013 30K6AUD 



Trislate Bipolar 

Open C Bipolar 

Open Collector 

Bipolar 

Trislate 

TTL Open Collector 

TTL Open Collector 

Sialic 



JE600 HEXADECIMAL 
ENCODER KIT 



FT 



I 



FEATURES: 

• Full 8 tort latched Output lor micro- 
processor use 

• 3 User Define keys with one being bi- 
stable operation 

■ Debounce circuit provided lor all 19 
keys 



mector 



i tries 

indard 16 pin 



■5VDC required lot operations 
FULL 8 BIT LATCHED OUTPUT— 19 KEYBOARD 
The JE600 Encodei Keyboard provides two separate beiadecimal 
digits produced Irom sequential key entries lo allow direct prog- 
ramming lor 6 bil microprocessor or 8 bit memory cucuils Three 
(3) addilional keys are provided tor user operalions with one having 
a bisiabie oulput available. The outputs are latched and moniiored 
wiih LED readouts Alsc- included is a key eniry strobe 

JE600 $59.95 

Hexadecimal Keypad only $1 4.95 



DIGITAL 
THERMOMETER KIT 




■ Dual sensors— switching control for in- 
door/outdoor or dual monitoring 

• Continuous LED .8" ht. display 

■ Range: -40°F to 199°F / -40°C to 100°C 
■Accuracy: ±1°nomlnal 

■Set for Fahrenheit or Celsius reading 
■Sim. walnut case - AC wall adapter Incl. 
■Size: 3-1/4"Hx6-5/8"Wx1-3/8"D 

JE300 $39.95 



62-Key ASCII Encoded Keyboard Kit 




The JE610 62-Key ASCII Encoded Keyboard 
Kit can be interfaced into most any com- 
puter system. The JE610 Kit comes com- 
plete with an industrial grade keyboard 
switch assembly {62 keys), IC's, sockets, 
connector, electronic components and a 
double-sided printed wiring board. The 
keyboard assembly requires +5V @ 150mA 
and —12V @ 10mA for operation. 



FEATURES: 

•60 Keys generate the full 128 char- 
acters, upper and) tower case ASCII 
sat 

• Fully buffered 

• 2 user-define keys provided for 
custom applications 

• Caps lock for upper case only 
alpha characters 

•Utilizes a 2376 (40 pin) encoder 

read only memory chip 
•Outputs directly compatible with 

TTL/DTL or MOS logic arrays 
•Easy interfacing with a 16-pin dip 

or 18-pin edge connector 

JE610 $79.95 

62-Key Keyboard only. .$34.95 



HICKOK 



LX303 Portable LCD Digital Multimeter 



• lOthnV ucfsv 




™..™fn 



( r.,i,;'.i* 



LX303 Digital Multimeter $74.95 

RC-3 116V AC ADAPTE R 7.50 

CC-3 PADDED CARRYING CASE 7.50 

VP-10 X10 DC PROBE ADAPTER (Up lo I OK] , 14.95 

VP-40 40kV DC PROBE 35.00 

CS-1 10 Amp DC Current Shun! 14.95 

$10.00 Min. Order - U.S. Funds Only Spec Sheets - 25rf 

Calif. Residents Add 6% Sales Tax 1980 Catalog Available -Send 41^ stamp 

Postage — Add 5% plus $1 Insurance (if desired) 

■ ■■■■■■^■H PHONE 

ISoA l ameco w o e r s s e 

MAIL ORDER ELECTRONICS - WORLDWIDE 

1355 SHOREWAY ROAD, BELMONT, CA 94002 

ADVERTISED PRICES GOOD THRU FEBRUARY 




The Incredible 
"Pennywhistle 103" 

v>l0y.95 Kit Only 

Thn Pennywtilttfe 103 is capable cf recording data lo anil from audio tape without 

critical speed requirements tor the recorder and it is able to communicate directly with 

another modern and terminal (or ;elephone "hamming" and communications. In 

addition, it isf ree of critical adjustments and is built with non-precision, readily available 

parts. 

Data Transmission Method Frequency-Shift Keying, full-duple* (half-duplex 

selectable). 

Maximum Dafa Rate 350 Baud, 

Dala Formal Asynchronous Serial (return !o mark level required 

between each character). 
Racslw Channel Frequencies . . .2025 Hz for space; 2225 Hz for mark. 
Transmit Channel Frequencies . . Switch selectable: Low (normal) = 1070 space, 

1270 mark; High = 025 space, 2225 mark. 

Receive Sensitivity -46 dbm acoustically coupled. 

Transmll Laval -15 dbm nominal. Adjustable from -6 dbm 

to -20 dbm. 
Racaiva Frequency TolBrance ...Frequency reference aulomaiically adjusts to 

allow for operation between 1 BOO Hz and 2400 Hz. 
Digital Dala Inlerface EIA RS-232C or 20 mA current loop (receiver is 

optoisolated and non-polar). 

Power Requirements 120 VAC, single phase. 10 Watts. 

Physical All components mount on a single 5" by 9" 

piinted circuit board. All components included. 
Requires a VOM, Audio Oscillator, Freq uency Counter and/or Oscilloscope lo align 

TRS-80 
16K Conversion Kit 

Expand your 4K TRS-80 System to 16K. 
Kit comes complete with: 

* 8 each UPD416- 1 (16K Dynamic Rams ) 250NS 

* Documentation for conversion 

TRS-16K $75.00 





•30 AWG wire ■ .025" square posts 
•Daisy chain or • Built-in cut off 

point-to-point • Includes 50 ft. wire 
• No stripping or slitting required- 
just wrap 

Wire 



Part No. 
JW-I-B 

JW-1W 
JW-1-Y 
JW-1-R 



White 
Yellow 
Red 



Prica 

$14.95 
14.95 
14.95 
14.95 



JUST UURAP" Replacement Wire 



Pan No. 

R-JW-B 
R-JW-W 
R-JW-Y 
R-JW-R 



Blue 50 ft. , 

White 50 ft. 

Yellow 50 ft. i 

Red 50 ft. i 



Pries 

$2.98 
2.98 
2.98 
2.98 



JUST WRAP' Unwrap Tool $3.49 




JUST Ul/RAP" Kit «50 ft. ea: blue, white, red. 
yellow wire 
• JUST WRAP Tool •Unwrapping Tool 

JWK-6 $24.95 




Vacuum Vise 

Vacuum-based light-duty 
vise for small components 
and assemblies. AFJS con- 
struction. 1«" jaws, 1J4" 
travel. Can be permanently 
installed. 



VV-1 $3.49 




EPROM 
Erasing 
Lamp 



•Erases 2708, 2716, 1702A, 5203Q, 5204Q, etc. 
•Erases up to 4 chips within 20 minutes. 
•Maintains constant exposure distance of one inch 

Special conductive foam liner eliminates static build-up 
•Built-in safety lock to prevent UV exposure 
• Compact - only 7-5/8" x 2-7/8" x 2" 

Complete with holding tray for 4 chips 

UVS-11E $69.95 



■P 

-©■ 



JOYSTICK 

•2 each 100K pots (Linear 

Taper) 
•Printed Circuit Board 

Mount 
•Size: 1 " x 1-3/1 6" x 1-3/1 6" 



JOYSTICK . 



$4.95 J 



Circle 217 on inquiry card. 



BYTE February 1980 245 




One-Stop Component Center 
AUTHORIZED DISTRIBUTORS 



ALABAMA 

Cropwell Tucker Bros. 

Huntsville Industrial Electronic Supply 

Mobile Lafayette Radio Electronics 
ALASKA 

Anchorage The Electronic Company 

Anchorage TV Mart 
ARIZONA 

Flagstaff Jim's Audio & Stereo Repair 

Sierra Vista B & S Electronics 

Yuma Yuma Electronics 
ARKANSAS 

Little Rock Southern Electronics Company 

CALIFORNIA 

Anaheim Heathkit Electronic Center 

Azusa Amco Electronics 

Bellflower Earl's Hobby Shop 

Berkeley At Lasher Electronics 

Brea Century Electronics 

Buena Park Ford Electronics 

Buena Park S.J. Electronics 

Chula Vista Lion Electronics 

Cypress SCR Electronics 
Davis Paradyne Consumer Electronics 

El Mon te Kimball & Stark 

Fontana Fontana Electronics 

Fresno Sparky Electronics 

Glendale Eagle Electronics 

Harbor City Buff's Electronics 

Hawaiian Gardens Carson Electronics 

Hollywood Pacific Radio Exchange 

La Habra A.B.C. Electronics 

Lancaster Consumer Electronics 

Long Beach Scott Radio Supply Inc. 

Mission Viejo Tower Electronics Corp. 

Modesto Computer Magic 

Modesto Pacific Radio 

Mon terey Zackit 

Morro Bay Coast Electronics 

National City Willy's Electronics 

Oceanside Electronic Center 

Oxnard Dow Radio 

Palmdale Radio Shack A. S. C Palmdaie 

Palo Alto U.S. Electronics 

Palo Alto Zack Electronics 

Pasadena Dow Radio inc. 

Paso Robles Mission Electronics 

Redding Radio Mart 

Sacramento Heathkit Electronic Center 

Sacramento Zackit 

Salinas Salinas Radio 

San Carlos J&H Outlet Store 
San Diego Radio Shack A.S.C. Mira Mesa 

San Diego Byte Shop 

San Fernando San Fernando Electronics 

San Francisco Zack Electronics 
San Jose Peninsula Electronic Supply Inc. 

San Jose United Radio & TV Supply 
San Luis Obispo Mid-State Electronic Supply 

San Rafael Electronics Plus 

Santa Barbara Lombard Electronics 

Santa Cruz Santa Cruz Electronics 

Santa Fe Springs Industrial Electronics 

Santa Maria Cap's Communications 

Santa Rosa Electronics Inc. 

South Lake Tahoe CalPine Electronics 

Suisun City Byte Shop 

Sunnyvale Sunnyvale Electronics 

Torrance SE Electronics 

Torrance Torrance Electronics 

Vacaville D.C. Electronics 

Vallejo Zackit 
Van Nuys Thrifty Electronics Supply Inc. 

Walnut Creek MicroSun Computer Center 

Westminster JK Electronics 

Whittier D & S Electronics 

Whittier Whittier Electronics Company 
COLORADO 

Aurora Aurora Electronics 
Colorado Springs Centennial Electronics Inc. 

Denver Amp tec Inc. 

Denver Mt. Coin Distributing Co. 
CONNECTICUT 

Avon Heathkit Electronic Center 

Bridgeport Bridgeport Computer 

Milford Daz Electronics 
New Haven Customized Computer Systems 

Westport Computerworks 
DELAWARE 

New Castle Delaware Amateur Supply 
FLORIDA 

Ft. Lauderdale Computers For You 

Gainesville Lafayette Radio 

Hialeah Heathkit Electronic Center 
Lakeland Lakeland Specialty Electronics 

Miami Herman Electronics 

Miami N & G Distributors 

Oakland Park Lafayette Radio 

Orlando Southeast Micro-Data Corp. 

Panama City Bay-Mar Electronics Inc. 

Pensacola Grice Electronics Inc. 

Tampa AMF Electronics 

Tampa Microcomputer Systems 



GEORGIA 

Atlanta 

A tlan ta 

Columbus 

Stone Mountain 

HAWAII 

Aiea 

Honolulu 

IDAHO 

Boise 

Caldwell 

ILLINOIS 

Carbonda/e 

Decatur 

Evanston 

Gro veland 



Atlanta Computer Mart 

CompuShop 

Radio Wholesale 

Coleman's Electronics 

Delcoms Hawaii 
Integrated Circuit Supply 

Custom Electronics 
A-Gem Supply Inc. 

Picks Electronics 
Main Street Computer Co. 
Tri-State Electronic Corp. 
Moyer Electronics 



MICHIGAN (Continued) 

Pontiac Electronic Supply 

Port Huron Main TV Radio Electronics Inc. 

Saginaw Electronic Mart 

St. Clair Shores Bell Electronics 

Sterling Heights Lafayette Radio 

Traverse City Traverse City Electronic Supply 



Mount Prospect Tri-State Electronic Corp. 

Niles Computer Land 

Normal B-N Computer Works 

Peoria Computer Land of Peoria 

Peoria Warren Radio Co. 

Rockford Computer Store of Rockford 

Schaumburg Data Domain of Schaumburg 

Skokie 'Lilfpuie Computer 

Villa Park Melvin Electronics 
INDIANA 

East Chicago Aero Electronics Carp. 

Evansville Hutch & Son Inc. 

Gary Caliimet Electronic Supply 
IOWA 

Ames Electronic Supply Inc. 
Clinton Bridge Electronics Computer Center 

Davenport Memory Bank 

Des Moines Gifford Brown Incorporated 

Des Moines Radio Trade Supply Co. 
KANSAS 

Hutchinson Hutchinson Electronics 

Kansas City Electronic Surplus Sales 

Mission Heathkit Electronic Center 

Salina Electronics Inc. 
Wichita Amateur Radio Equipment Co. 
KENTUCKY 

Lexington Radio Electronic Equipment Co. 

Louisville Peerless Electronic Equipment Co. 

Richmond Madison County Electronics 
LOUISIANA 

Baton Rouge Davis Electronics Supply Co- 
Baton Rouge Menard Electronics Inc. 
Baton Rouge Pelican Electronics 
Houma Pelican Electronics 
Lake Charles Wholesale Radio & Equipment 
Metairie Pelican Electronics 
New Orleans Wm. B. Allen Supply Co. 
MARYLAND 

Annapolis J & M Electronics Inc. 

Baltimore American Distributing Co. 

Baltimore Everything Electronic 

Baltimore Harco Electronics 

Baltimore Tritronics Inc. 

Churchville Church ville Electronics 

Damascus Damascus CB 
Frederick Frederick Computer Products Inc. 

Glen Burnie Revacto 

Hagerstown Custom Computing Inc. 

La Vale J & M Electronics 

Rockvil/e Computer Workshop 

Rockvilie Heathkit Electronic Canter 

Silver Spring Computers Etc. 

Towson BaynesvUla Electronic Inc. 

Towson Computers, Etc. 

Towson Computers Unlimited 

Towson Heathkit Electronic Center 
MASSACHUSETTS 

Peabody Heathkit Electronic Center 

Pittsfield Pittsfield Radio Co. Inc. 

Waltham Computer Mart Inc. 

Wellesley Heathkit Electronic Center 

Worcester RM Electronics Inc. 
MICHIGAN 

Adrian E & B Electronics inc. 

Ann Arbor Lafayette Radio 

Ann Arbor Wedemeyer Electronic Supply 

Bay City Kinde Distributing Company 

Canton The Electronic Connection 
Clawson Radio Supply & Engineering Co. 

Detroit Heathkit Electronic Center 

East Detroit Heathkit Electronic Center 

East Lansing Lafayette Radio 

Flint Hobby Electronic Center 

Flint Shand Electronics Inc. 

Garden City Computer Center 

Grand Rapids Micro Computer World 

Grand Rapids Radio Parts Inc. 

Grand Rapids Warren Radio Company 

Jackson Fulton Radio Supply 

Lansing Fulton Radio Supply Co. 

Livonia Lafayette Radio 
Livonia Radio Supply & Engineering Co. Inc. 

Midland Computronix Corporation 

Milan C& S Electronics Mart L td. 

Muskegon H.R. Electronics 

Niles Niles Radio Supply 

Oak Park Lafayette Radio 



MINNESOTA 

Duluth 

Hopkins 

Minneapolis 

St Paul 

Winona 

MISSOURI 

Bridgeton 

El Dorado Springs 

Florissant 

MONTANA 

Billings 



Northwest Radio of Duluth Inc. 

Hedthkit Electronic Center 

Pal Electronics 

Heathkit Electronic Center 

Hiawatha Electronics Inc. 



Forsythe Computers 

Beckman Electronics 

Computer Country 



Bozeman Electronic Sarvice & Distributing Inc. 



Great Falls 
NEBRASKA 

L incoln 

Lincoln 

North Platte 

Omaha 

Omaha 

NEVADA 

Las Vegas 

NEW JERSEY 

Cherry Hill 

Fair Lawn 

Ocean 

Pennsauken 

Pompton Lakes 

Ramsey 

Vineland 

NEW MEXICO 

Farmington 

NEW YORK 

Albany 

Albany 

Albany 

8/oomington 

Buffalo 

Cortland 

Endwell 

Ithaca 

Jamestown 

Jericho 

Kingston 

Kingston 

Middletown 

Newburgh 

New York 

New York 

Orchard Park 

Peek skill 

Poughkeepsie 

North White Plains 

Rensselaer 



Conley Radio Supply 



Arts Electronics 

Altair Computer Center 

Scott Electronic Supply Inc. 

Scott Electronic Supply Corp. 

Heathkit Electronic Center 

Omaha Computer Store 



Rochester 

Troy 

Utlca 

Vestal 

Wappingers Falls 

White Plains 

NORTH CAROLINA 

Greenville 

Morehead City 

Raleigh 

NORTH DAKOTA 

Fargo 

Fargo 

OHIO 

Bucyrus 

Cincinnati 

Columbus 

Reynoldsburg 

Toledo 

Wick/iffe 

Youngstown 

OKLAHOMA 

Oklahoma City 

Oklahoma City 

Oklahoma City 

Tulsa 

OREGON 

Albany 

Beaverton 

Corvallis 

Eugene 

Ontario 

Portland 

Salem 

Salem 

PENNSYLVANIA 

Braddock 

Chambersburg 

Drexel Hill 

Drums 

Erie 



Century 23 

The Computer Emporium 
Heathkit Electronic Center 
Heathkit Electronic Center 
Lafayette Radio 
Computer Corner 
Typetronic Computer Store 
Lafayette Radio Electronics 

Micro-Computer Service 

Fort Orange Electronics 

Action Audio Inc. 

Greylock Electronics 

Stansifer Radio Co. Inc. 

Radio Equipment Corp. 

Action Audio Inc. 

Computer Tree Inc. 

Action Audio Inc. 

Warren Radio 

Heathkit Electronic Center 

Action Audio Inc. 

Greylock Electronics 

Action Audio Inc. 

Action Audio Inc. 

Aristo Craft 

Manhattan Electronics Corp. 

Radio Equipment Corp. 

Action Audio Inc. 

Greylock Electronics 

Heathkit Electronic Center 

Corn-Tech Electronics 



Heathkit Electronic Center 

Trojan Electronics 

Am-Com Electronics 

Harvey Electronics 

Action Audio Inc. 

The Computer Corner 

Pair Electronics 

Baer Electronic Systems 

Byte Shop of Raleigh 

The Computer Company 
S& S Electronics 

Mead Electronics 
Heathkit Electronic Center 
Heathkit Electronic Center 
Universal Amateur Radio 
Heathkit Electronic Center 
Amateur Electronic Supply 
Ross Radio Company 

Bits, Bytes & Micros 
Heathkit Electronic Center 
Trice Wholesale Electronics 

High Technology 



PENNSYLVANIA (Continued) 

Philadelphia Heathkit Electronic Center 
Philadelphia Resco Electronics (Market St.) 

Phoenixville Stevens Electronics 

Pittsburgh Heathkit Electronic Center 

Pittsburgh Tydings Company 

Wilkes Barre Hamline Electronics 

York G.Y.C. Company 
RHODE ISLAND 

Cranston Jabbour Electronics City 

Pawtucket Jabbour Electronics City 

Warwick Heathkit Electronic Center 
TENNESSEE 

Clarksville Masstronics 

Cookevil/e Wagnon's Stereo Center 

Nashville Electra Distributing Co. 
Knoxvi/le Shields Electronics Supply Inc. 

Memphis Bluff City Electronics 
Memphis Sere-Rose & Spencer Electronics 

Memphis Warren Radio Company 
Nashville Eddie Warner's Parts Company 

Oakridge National Electronics 

Tullahoma H & H Electronics Co. Inc. 
TEXAS 

Beaumont Electro-Hut 

Dallas CompuShop 

Dallas Heathkit Electronic Center 

Dallas Ram Micro Systems 

Fort Worth The Ingenuity Concept 

Houston Interactive Computers 

McAllen Broadway Electronics 

McAllen Carlos Franco Electronics 

San Antonio Appliance & Equipment Co. 
San Antonio Sherman Electronics Supply Inc. 
UTAH 

Midvale Heathkit Electronic Center 

Provo Alpine Electronic Supply Co. 

Salt Lake City Best Distributing 

Salt Lake City Computer/and of Salt Lake 
VERMONT 

Essex Junction Lafayette Radio 
VIRGINIA 

Alexandria Computers Plus Inc. 

Alexandria Heathkit Electronic Center 
Arlington Arlington Electronic Wholesalers 

Blacksburg Scotty's Radio & TV Inc. 

Charlottesville Graves Electronics 

Colonial Heights Southside Radio Comm. 

Falls Church Crossroad Electronics 

Hampton Electronic Sales Inc. 

McLean Tyson's Computer Emporium 

Norfolk Avec Electronics Corp. 

Norfolk Priest Electronics 

Portsmouth Electronics Unlimited 

Richmond Avec Electronics Corp. 

Vienna Electronic Equipment Bank 

Virginia Beach Heathkit Electronic Center 

Warrenton Radio Shack 
WASHINGTON 

Bellevue ABC Communications 

Everett ABC Communications 

Kennewick C & J Electronics Inc. 

Longview Progress Electronics 

Moses Lake Ron's Electronics 

Pasco Riverview Electronics 

Richland C & J Electronics 

Seattle ABC Communications 

Seattle Amateur Radio Supply 

Seattle Empire Electronics 

Spokane Personal Computers 

Tacoma C & G Electronics 

Tacoma Northwest Radio Supply 
WEST VIRGINIA 

Morgantown The Computer Corner 

Morgantown Electro Distributing Co. Inc. 
Wheeling Lafayette Radio Associate Store 
WISCONSIN 

West AIUs Olson Electronics 



Paoli 



Oregon Ham Sales 

Norvac Electronics 

Zero-Gee Books 

Eugene Amateur Radio Supply 

Miller Electronics 

Portland Radio Supply 

Comm-Shack 

Computer Pathways 

Left Electronics 

Sunrise Electronic Distributing 

Kass Electronics Distributors 

Mr. D's Digital Electronics 

Warren Radio 



CompuShop Alberta Ltd. 



Personal Computer Corporation 



CANADA 

Alberta: 

Calgary 

British Columbia: 

Prince George Elwest Technical Services Ltd. 

Vancouver CompuShop 

Ontario: 

Toronto House of Computers 

ENGLAND 

Berkshire NewBear Computing Store 

GUAM Marianas Electronics 

PANAMA 

Panama City Sonitel, S.A. 

Panama City Tropelco. S.A. 

SINGAPORE Applied Digital System 

SINGAPORE Inter-Trade <PTE.) Ltd. 

SINGAPORE Sys-Tech 

SWEDEN 

Stockholm LSI Electronics HB 

Umea tnterkomponent 

WEST INDIES 

Port of Spain, Trinidad The Hobby Centre 



For Distributor Information, write or phone JIM-PAK® 1355 Shoreway Road, Belmont, CA 94002 (415) 592-8097 



246 BYTE February 1980 



Jag Quality Kits 



Function Generator Kit 




Provides three basic wave- 
forms: sine, triangle and 
square wave. Frequency 
range from 1 Hz to 100K 
Hz. Output amplitude from 
volts to over 6 volts (peak 
to peak). Uses a 1 2V supply 
or a ±6V split supply. In- 
cludes chip, P.C. Board, 
components & instructions. 



JE2206B $19.95 



Digital Thermometer Kit 




Dual sensors — switching control for indoor/outdoor 
or dual monitoring. Continuous LED .8" ht. display. 
Range: -40°F to 199°F / -40°C to 100°C. Accuracy 
±1° nominal. Set for Fahrenheit or Celsius. Simulated 
walnut case. AC wall adapter included. 
Size: 334"h x 6-5/8"w x 1-3/8"d. 

JE300 $39.95 



Digital Stopwatch Kit 



PDCKfc T 
SlUFfeffTTii 



Use Intersil 7205 Chip. Plated 
thru double-sided P.C. Board, 
Red LED display. Times to 
59 minutes, 59.59 seconds 
with auto reset. Quartz crystal 
controlled. Three stopwatches 
in one: single event, split 
(cummulative) and taylor (se- 
quential timing). Uses3penlite 
batteries. 

Size: 4.5" x 2.15" x .90" 



JE900 $39.95 



4-Digit Clock Kit 



6- Digit Clock Kit 





Jumbo 
6-Digit Clock Kit 




Bright .357" ht. red display. Sequential flashing 
colon. 12 or 24 hour operation. Black extruded alu- 
minum case. Pressure switches for hours, minutesand 
hold functions. Includes all components, case and 
wall transformer. Size: 3'A" x 1 %" x 1 S4" 

JE730 $14.95 



Bright .300 ht. common cathode display. Uses MM- 
5314 clock chip. Switches for hours, minutes and 
hold functions. Hours easily viewable to 20 ft. Simu- 
lated walnut case. 1 1 5VAC operation. 1 2 or 24 hour 
operation. Includes all components, case and wall 
transformer. Size: 6%" x 3-1/8" x 1%" 

JE701 $19.95 



Four .630" ht. and two .300" ht. comm. anode dis- 
plays. Uses MM5314 clock chip. Switches for hrs., 
mins., and hold functions. Hours viewable to 30 ft. 
Sim. walnut case. 1 1 5VAC operation. 1 2 or 24 hour 
operation. Incl. all components, case and wall trans- 
former. Size: 6%" x3-1/8" x 1%" 

JE747 $29.95 



Regulated 
Power Supply Kit 



Multi-Voltage 
Board Kit 



Variable 
Power Supply Kit 




Uses LM309K. Heat 
sink provided. PC 
board construction. 
Provides solid 1 amp 
@ 5 volts. Includes 
components, hard- 
ware & instructions. 
Size:3H"x5"x2"h 



i tfJ 



^t 



ADAPTS TO JE200 
SUPPLIES ±5V, ±9V and ±12V 

Independent load rating at single 
terminal. ±12V:160mA, ±9V:200 
mA, -5V:250mA. DC/DC convert- 
er with +5V input. Toriodal hi- 
speed switching XMFR. Short 
circuit protection. PC board con- 
struction. Piggy-back to JE200 
board. Size: 3 1 /s" x 2" x 9/16"h 




Full 1.5 amp @ 5-10V out- 
put. Up to .5 amp @ 15V 
output. Heavy duty trans- 
former. Three-terminal I.C. 
voltage regulator. Heat sink 
provided for cooling effi- 
ciency. PC board construc- 
tion. 120VAC input. 
Size: 3 1 / 3 " x 5" x 2"h 



JE200 $14.95 



JE205 $12.95 



JE210 $19.95 



62-Key ASCII 
Encoded Keyboard Kit 




The JE610 ASCII KEYBOARD KIT can be interfaced into most any computer 
system. The JE610 kit comes complete with an industrial grade keyboard switch 
assembly (62-keys), IC's, sockets, connector, electronic components and a double- 
sided printed wiring board. The keyboard assembly requires +5V @ 150mA and 
— 12V@ 1 0mA for operation. Features: 60 keys generate the full 128 characters, 
upper and lower case ASCII set. Fully buffered. Two user-define keys provided 
for custom applications. Caps lock for upper case-only alpha characters. Utilizes 
a 2376 (40-pin) encoder read-only memory chip. Outputs directly compatible 
with TTL/DTL or MOS logic arrays. Easy interfacing with a 16-pin dip or 18-pin 
edge connector. 

JE610 $79.95 



Hexadecimal Encoder Kit 

i% 

M 



FULL 8-BIT LATCHED OUTPUT - 19-KEY KEYBOARD 
The JE600 ENCODER KEYBOARD provides two separate hexadecimal digits 
produced from sequential key entries to allow direct programming for 8-bit 
microprocessor or 8-bit memory circuits. Three (3) additional keys are provided 
for user operations with one having a bistable output available. The outputs are 
latched and monitored with 9 LED readouts. Also included is a key entry strobe. 
Features: Full 8-bit latched output for microprocessor use. Three user-define 
keys with one being bistable operation. Debounce circuit provided for all 19 keys. 
9 LED readouts to verify entries. Easy interfacing with standard 16-pin IC con- 
nector. Only +5VDC required for operation. 

JE600 $59.95 




(Prices Subject To Change) 



Circle 218 on inquiry card. 



BYTE February 1980 



247 



ISEE OUR 52 PAGE AD IN JANUARY BYTEl 



DISC 
DRIVES 




SD EXPANDORAM The Ultimate S-100 Memory 



The EXPANDORAM is available in versions from 16K 
up to 64K, so for a minimum Investment you can have 
a memory system that will grow with your needs. This 
Is a dynamic memory with the Irtvlsable onboard 
refresh, and IT WORKS! 

IMSAI. SOL-8, Cromenco. 



. ~.rJ&W&:...^-- 



'WB*\~*U"\ gH^jwr^ 



EXPANDO 64 

List Price 

$385.00 

$550.00 

$715.00 

$880.00 



16K 
32 K 
48 K 
64 K 



KIT (4116): 
Sale Price 

$239.00 
$309.00 
$379.00 
$449.00 



Bank Selectable 

Phantom 

Power 8VDC, ± 16VDC, 5 Watts 

Lowest Cost Per Bit 

Uses Popular 41 16 RAMS 

PC Board Is doubled solder masked and has 

silk-screen parts layout. 

Extensive documentation clearly written 

Complete Kit Includes all Sockets lor 84K 

Memory access time: 375ns, Cycle time: 500ns. 

No wait states required. 

16K boundrles and Protection via Dip Switches 

Designed to work with Z-BO, 8080, 8050 CPU's 



P 

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DISC CONTROLLER 
SD "VERSAFLOPPY" KIT 

The Versatile Floppy Disk 
Controller List Price 
$250.00 
SALE PRICE 



$189.95 



VERSAFLOPPY II 

DOUBLE DENSITY, DOUBLE SIDED, DISC.CONTROLLER 




GENERAL DESCRI 
Veisalloppy II is I 
controller that in 



inch diskette 'and 129, 9Z0 bytes per 
side on a live inch minidiskette The 
Varsalloppy II direclly conttols many 
popular disk drives. These Include: 
Shugarl SA400 and SA450; Shugart 
SA0OO and 5A850; Mayllower MFESOO 
and MFE700: Per Sci 70 and 277; and 
Siemans, B5I-105. 

• S-100 BuslEEE Standard 
Compatible 

• IBM3740 Compatible Soft 
Sectored Formal tor Single 



ividos Control lor Double 

led Operation 

eiates with Z80, 8080, and 8085 



SDS-VERSAFLOPPY II KIT List Price Sale Price 

$350.00 $325.95 



SDOS Disk Operating Sysler 



SHOP & COMPARE SPECIAL 




M-XVI 

The true 16K Static Ram module 

(or S-100 bus systems. 

ASSEMBLED ft TESTED - 100% BURN IN 
The M-XVI gives you unbelievable expansion 
capability la' youl 5 too •,.,$ system oven beyond 
64K. Mani.iact.te:] to mo b gtmst .nd.stty sian 



iobt), 



m 
m 



FEATURES ' 

• Fully static 

• Uses popuia' 

• + 5 voll opet 

• Bank Select . 
and bank byt. 

•Phanlom line capability 
•Addre 



201BBA 450ns 2MHZ Reg.$349.95 
2016BB 300ns 4MHZ Reg. $389.95 
2016BY Bare Board only 






■o addie 



Sale Priced 
$295.00 
$329.00 
$29.95 



•FR.4 epoxy PC boards 



THE MICROBYTE M32KSS 
32K STATIC MEMORY BOARD 
ASSEMBLED & TESTED * 

SAVE $120.00 

• Fully S500 Bus Compatible, IMSAI, SOL, ALTAIR. ALPHA MICRO, • Uses 
National's Low Power 5257 4Rxl Static Rams • 2 MHz or dMHz operation. • Gold 
contacts for higher reliability. • On board single 5 amp regulator. • On board single 
5 amp regulator • Thermally designed heat sink (board operating temperature 0° — 
70°C} ■ Commercially designed power bus. 7 ground bus bars, 0.I ul decoupling 
capacitors. ■ Fully trlslate buttered. • Inputs fully low power Shottky Schmilt, Trig- 
ger buffered on all address and data lines. ■ Phantom is |umper selectable to pin 67 

• Each <tK hardware or software selectable. • One on board 6-bit output port 
enables or disables the 32K in 4K blocks ■ Selectable port address. ■ 4K banks can 
be selected oi disabled on power on clear or reset. ■ Will operate with or without 
front panel • Compatible with ALPHA MICRO, with extended memory management 
for selection beyond 64K • No DMA restriction. ■ Low power consumption 2 3-25 
amps. • Fully warranted for 120 days from date of shipment 

ASSEMBLED & TESTED shipping weight 2 lbs 




M32 KSS-H (4 MHz) 

List $680 

SALE $560.00 



M32 KSS-L (2 MHz) 

List $650 

SALE $530.00 




IO 

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> 



With On-Board RAM, PROM, CTC 

• S-100 Bus Compatible 

• Z80 Central Processing Unit 

• 1024 Bytes of Random Access Memory 

• 8K Bytes of PROM using 2716 

• Parallel Input and Output Ports 

• Four Channel Counter/Timer (Z80-CTC) 

• Software Programmable Baud Rate Generator 

• No Front Panel Required for Operation 

List Price Sale Price 

SDS-SBC-100 2MHZ KIT . $295.00 $249 . 95 
SDS-SBC-200 4MHZ KIT. $320. 00 $289.95 



> 

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VDB-8024 VIDEO DISPLAY BOARD 

With on-board Z80 Microprocessor 

S-100 bus Compatible 

Full 80 Characters by 24 Lines Display 

Characters Displayed by High Resolution 7 x 10 

Matrix 

Composite or TTL Video Output 

Keyboard Power and Interface 

Forward and Reverse Scrolling Capability 

Blinking, Underlining, Field Reverse, 

Field Protect and Combinations 

Full Cursor Control 

96 Upper and Lower Case Characters 

32 Special Character Set 

128 Additional User Programmable Characters 

(Optional) 

On-Board Z80 Microprocessor 

2K Bytes Independent On-Board RAM Memory 

Glitch-Free Display 

List Price Sale Price 

SDS-VDB-8024 KIT $370.00 $329.95 



»f*S»lBS 



PROM-100 

Programming Board 
for PROM Development 



NEW 



SD SYSTEMS' PROM-100 is a versatile PROM pre 
gramming board offering complete EPROM program- 
ming capability. The board operates on the industry 
standard S-100 Bus. Support software verifies the 
erasure of EPROM and verifies the loaded program. 
SD SYSTEMS' PROM-100 offers a support-software 
listing with its operations manual. 

• S-100 Bus Compatible 

• Programs the Following EPROM s: 2708, Intel 
2758, 2716, 2732 and Texas Instruments 2516 

• Dip Switch Selection of EPROM type 

• 25 VDC Programming Pulse Generated On Board 

• Maximum Programming time: 16,384 Bits in 
100 Seconds 

• Power Requirement: +8VDC at 300 ma.; 

+ 16 VDC atr 100 ma.; - 16 VDC at 60 ma. 

• TTL compatible 

• Software Provides for Reading of Object File 
from SDOS, CP/M or PROM and Programming 
into EPROM 

• Program Verification • Verification of Erasure 

• Zero Insertion Force Socket 

List Price Sale Price 

SDS-PROM-100 KIT. $200.00 $1-75.00 



PRIORITY ONE ELECTRONICS® 

16723K Roscoe Blvd. Sepulveda, CA 91343 

Terms: Visa, MC, BAC, Check, Money Ordar, CO.D. U.S. Funds Only. CA residents add 6% 3ales ta: 
Minimum order $10.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handlinj 
MINIMUM $2.50. Excess refunded. Just in case . . . please include your phone no. 
Prices subject to change without notice. 
We will do our best lo malnlain prices thru Feb. 1980 OEM and Institutional 

phone orders welcome (213) 894-8171, (800) 423-5633 inquiries invited. 



% 



800- 
423-5633 

EXCEPT 

CA.AK.HI. 

(213)894-8171 




Z80 STARTER KIT 
A Complete Microcomputer On A Board 

• Z80 CPU with 158 Instructions 

• On-Board Keyboard and Display 

• On-Board PROM Programmer for Single 
Voltage PROMS (2716, 2758, TI2516) 

• Kansas City Standard Cassette Interface 

• Simple Key Controlled Audio Cassette Load 
and Dump 

• Expansion Provision for Mounting Two 
S-100 Connectors (Sockets Not Included) 

• Wire Wrap Area for Custom Circuitry 

• Single Step through RAM or PROM 

• Memory Examine and Change 

• Port Examine and Change 

• Z80 CPU Register and Change 

• 2K Byte ZBUG Monitor in ROM 

• IK Bytes of RAM (Expandable to 2K Bytes) 

• A 4 Channel Hardware Counter/Timer (Z80-CTC) 

• Two Bi-Directional 8-Bit I/O Ports (Z80-P10) 

• Up to 5 Programmable Breakpoints 

• Switch Selectable PROM or Monitor Restart 

• Vectored Interrupts provided by Z80-CTC and 

List Price Sale Price 

SDS-Z80 STARTER KIT $340.00 $279.95 



ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633 



248 BYTE R-bruarv 



ISEE OUR 52 PAGE AD IN JANUARY BYTEl 



4 MHZ EXPANDORAM II KIT 

The S-100 Memory Board for the 80's 

SD SYSTEMS' ExpandoRAM II is a state-of-the-art • S-100 Bus Compatible 

dynamic RAM board with capacities from 16K bytes • Up to 4Mhz Operation 

(4116) to 256K bytes (4164). It operates on the industry • Expandable Memory from 16K to 256K 

S-100 Bus. The ExpandoRAM N's design allows eight, • DIP Switch Selectable Boundaries 



*ty 



boards to operate from the same S-100 Bus. Page 
mode operation provides the system with the capabil- 
ity of servicing multiple users without RAM in- 
terference. Invisible refresh and synchronization with 
wait states provide greater reliability, and processing 
speeds up to 4 Mhz. 

The ExpandoRAM II is compatible with most S-100 
CPU's based on the Z80 microprocessor. When other 
SD SYSTEMS 200 series boards are combined with the 
ExpandoRAM II, they create a microcomputer with ex- 
ceptional capabilities and features. 



Uses 16K (4115) or 64K (4164) Memory Devices 

Page Mode Operation Allows up to 8 Memory 

Boards on Bus 

Operates with Z80 CPU's 

Phantom Output Disable 

Invisible Refresh (Synchronized with 

Wait States) 




SDS ■ EXPANDOPRAM II KIT (4116) 

List Price Sale Price List Price Sale Price 

16K . . . $460.00 $295.00 48K . . . $960.00 $445.00 
32 K . . . $710.00 $370.00 64K . . $1210.00 $520.00 



8803 



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BOARD FOR 


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S100 BUS 


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glass w>l 


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glass Board wi 


2 ounce. 








In holes far loads 




Soldo > m. 






tithed a 














recooiacies wiirt ioocomacis|2 




I2S centers *U 


250 row spacing. 


Vecior w 


number R68I ■ 


.ormounis 10 rocep- 


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includes 


Ched Circuits a 


dinslruclKjnstoroplion 




es + SVdnuGNO<IOAMPS) ± 12V 


AMPS] C 


ireni ratings at 


BeiHIL-STO-I75wim 




Price: 
$29.50 



Plugboards 





8800V 

Universal Microcomputer /processor 
plugboard, use with S-100 bus Com- 
plete with heat sink & hardware 5 3"* 
10 x 1/16 ■ 

1-4 5-9 10-24 

S19.95 $17.95 515.95 

8801-1 
Same as 8800V except plain: less power 
buses & beat sink 

1-4 5-9 10-24 

$15.22 $13.79 $12.18 



3682 9.6" X 4.5" 

$12.97 

3682-2 6.5" X 4.5" 

$9.81 

Hi-Density Dual-ln-Line 
Plugboard for Wire Wrap 
with Power & Grd Bus 
Epoxy Glass 1/16" 44 
pin con. spaced .156 



3677 9.6"x4.5' 

$10.90 

3677-2 6.5" x 4.5" 

$9.74 

Gen. Purpose D.I. P. 
Boards with Bus Pattern 
tor Solder or Wire Wrap. 
Epoxy Glass 1/16" 44 
pine n. spaced .156 



ijiiil 



mull 

3662 6.5" x4. 5" 

$8.95 

3662-2 9.6" x4. 5" 

$11.45 

P pattern plugboards tor 
IC's Epoxy Glass 1/16" 
44pincon, spaced .156 



FMfl 

IllllllllllP 3690-12 
CARD EXTENDER 
Card Extender has 100 con- 
tacts 50 per side on .125 
centers-Attached connec- 
tor-is compatible with 
S-100 Bus Systems . $25.83 
3690 6.5" 22/44 pin .156 
ctrs. Extenders .... $13.17 



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CQ 1 (MSA) Style Card Guides S/S1.00 



S1O0.WWG50n00Con1 125clts. 3 LEVEL 
VIAE WRAP 025" sq. posts on .250 spac- 
d rows GOLD PLATED 



S100SE 50/100 Con! 125 ctrs. PIERCED 
SOLDER EYELET Tails GOLD 

1-4 5-9 10-24 

15.00 S4.50 S4.00 



S100-STG 50H0O Cont .125 ctrs. DIP 
SOLDER TAIL on 250 spaced tows lor 
VECTOR, IMSAI. CROMENCO mother 
boards GOLD plated 



1-4 
$4.10 



S3.80 



S100ALT 50/100 Conl .125 ctrs. 
SOLDER TAIL on HO spaced rows 
ALTAIR motherboards, GOLD plated. 
1-4 5-9 10-24 

$4.50 $4.25 $4.00 



(or 



Other Popular Edge Connectors 



D2244-5SE 22/44 Conl .156 Ctrs. PIERCED 
SOLDER EYELET tails GOLD plated. 
1-4 5-9 10-24 

$3.00 $2.60 $2.20 



RS232 & "D" TYPE CONNECTORS 

P = Plug-Male S = Sockel-Female C = Cover-Hood 



PART NO. 

OE-9P 

DE-9S 

DE-9C 

DA15P 

DA15S 

DA15C 

DB-25P 

DB-255 

OB51212-1 

DB1226-1A 

DB110963-3 

OC37P 

DC37S 

DC37C 

DD50P 

DD50S 

DDS0C 

D20418-S 



9 Pin Female 
9 Pin Cover 
15 Pin Male 
15 Pin Femal 
15 Pin Covef 
25 Pin Male 
25 Pin Female 

1 pc. Grey Hood 

2 pc. Black Hood 
2 pc. Grey Hood 
37 Pin Male 
37 Pin Female 
37 Pin Cover 
50 Pin Male 
50 Pin Female 
50 Pin Cover 



rW&fc. 



M 



/ ^"""■'"" Jh \ 

1 FEMALE ~ I ' 



Hardware Set (2 pain 

Connector lor CENTRONICS 700 SERIES: 

Amphenol 57-30360 for back of Centronics 700 Series pri 
1-4-59.00 5 up — $7 50 



1.50 
2.15 
1.50 
2.20 
3.20 
1.60 
2.90 
3.7S 
1.65 
1.90 
1.80 
3.95 
5.75 
2.20 
4.95 
7.50 
2.50 
1.00 



1.30 
2.05 
1.30 
2.00 
3.00 



2.60 


2.50 


3.65 


3.40 


1.40 


1.20 


1.60 


1.50 


1.55 


1.35 


3.80 


3.60 


nnil 


b,m 


1.95 


1.75 


4.75 


4.50 


7.20 


6.90 


2.20 


2.10 



1M6 VmOl BOARD 
m .042 dia holes on 
P» 0.1 spacing for IC's 

Phenolic PRICE 

PART NO. SIZE . 1-9 10-19 

64P44XXXP 4.5x6.5" $1.56 $1.40 

169P44XXXP 4.5x17" $3.69 $3.32 



Epoxy Glass 

64P44 
84P44 
169P44 
169P84 



4.5x6.5" 
4.5XB.5" 
4.5x17" 
8.5x17" 



$1.79 $1.61 
$2.21 $1.99 
$4.52 $4.07 
$8.83 $7.95 



3 LEVEL GOLD WIRE WRAP SOCKETS* 

Sockets purchased in multiples of 50 per type may be combined lor best price. 
1-9 10-24 25-99 100-249 250-999 




8 pin 
14 pin 
16 pin 
18 pin 
20 pin 
22 pin 
24 pin 
28 pin 
40 pin 



.40 
.44 
.55 
.70 
.90 
.95 
.95 
1.25 
1.65 



.36 
.43 



.85 
1.15 
1.45 



.55 
.75 



1.00 
1.35 




All sockets are GOLD 3 level closed entry. 2 level Tail Low 
Prolile. Tin Sockets and Dip Plugs available. CALL FOR QUOTATION. 



NOVATION CAT 
ACOUSTIC MODEM 




$174,95 



Regular 
$198.00 



• 0-300 Baud 

• Bell 103 



3M SCOTCH* BRAND 
DISKETTES 



740-OP 1/single SolMI 

740/2-OP 2/single Soft-It 

7A0-32P "(single 32 

7A0I2-32P 2r 1 single 32 

741-0 Kdouble Soil 



$3995 
S75.00 
$39.95 
$75.00 
$59.00 



'44-OK 1/singlc Soli (TRS-00) $51.00" 
44-10K 1/singlo Soft/10 $51.00" 

44-16K 1/singlrj Sottm $51.00" 

"Price includes Kas-etieMO Storage Box 

a $5.00 Value (TRS-80) 

"DON'T SETTLE FOR ANYTHING 

LESS THAN SCOTCH" 



TRS-80/APPLE 
MEMORY EXPANSION KITS 

/HIK'c QAIUIQ * rom Leading Manufacturers 

alio s MAivib (16Kx1 200/250ns) 

8 for $75.00 

Add $3.00 for programming Jumpers 

for TRS-80 Keyboard 




Answer, Originate 

PRIORITY 





PRICE: S18.98 



S same as 31[- 
rlth 14" bar to 

accomodate "S 1 00" 

boards. 

PRICE: S19.98 



PRICE:S14.49 



PANAVISE TILTS, TURNS, AND \ ■*«" 
ROTATES TO ANY POSITION. 
IT HOLDS YOUR WORK 
EXACTLY WHERE YOU WANT IT. 




PRICE: s1449 



DEALERS 
CALL FOR 




PRICING 



MEMORY MEMORY 

2102LIPCLuw Power 450ns in lots of 25 $1.10 
2102AL.-2L.ow Power 250ns in lots ot 25 $1.25 
2114-3L 1Kx4 300ns Low Power 8/$50.00 

5257-3L 4Kx1 300ns Low Power 8/$55.00 

2708 8K 450ns EPROM 8/$65.00 $9.00 

2716 16K 5 Volt Only EPROM $40.00 



ELECTRONICS® 




16723K Roscoe Blvd. Sepulveda CA 91343 

Terms: Visa, MC, BAC, Check, Money Order, C.O.D. U.S. Funds Only. CA residents add 6% sales tax. 
Minimum order $10.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling, 
MINIMUM $2.50. Excess refunded. Just in case . . . please include your phone no. 
Prices subject to change without notice. 

'SOCKET and CONNECTOR ... ... . ' . . . f . ., u Hfton _„. 

prices basad on gold, not We will do our best to maintain prices thru Feb. 1980 OEM and Institutional 

exceeding $376.00 per oz. phone orders welcome (21 3) 894-81 71 , (800) 423-5633 inquiries invited. 



ORDER 

1-800- 

except CA 

(213) 



Pectffi 



WRAP POST 

for .042 dia. holes 
(all boards on this page] 
T44/C pkg. 100 . . $ 2.34 
T44/M pkg. 

1000 $14.35 

A-13 hand installing 

tool $ 4.19 



TOLL FREE 

423-5633I 

., AK., HI., CALL 

894-8171 



ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633 



Circle 219 on inquiry card. 



Computer Products 



CHIP* 1* 



Of* 



MEMORY PRICES REDUCED !!! 



s Osy 



S7 "EA*S 



•our best selling memory 
EXPANDORAM 

EXPANDABLE TO 64K USING 4116 RAMS 




Interfaces with most popular S-100 boards 

Bank selectable; PHANTOM provision 

Draws only 5 watts fully populated 

Designed to work with Z-80, 8080, and 8085 systems 

No wait states required 

16K boundaries & protect via dip switches 

Kits come with sockets for full 64K 

Invisible refresh 

MEM-16130K (16K KIT) $239.95 

MEM-16130A (16K A&T) $289.95 

MEM-32131K (32K KIT) $309.95 

MEM-32131A (32K A&T) $359.95 

MEM-48132K (48K KIT) $379.95 

MEM-48132A (48K A&T) $429.95 

MEM-64133K (64K KIT) $449.95 

MEM-64133A (64K A&T) $499.95 

S D SYSTEMS 

PROM-100 

VERSATILE EPROM PROGRAMMER 




S-100 bus compatible (note: board height 7") 
Dip switch selects 2708, 2716, 2732, 2758, or 2516's 
25 VDC programming pulse generated on board 
Programming time only 100 seconds for 16K bits 
Support-software listing provided in manual 
Program and erasure verification 
Software provides for reading of object file from 
CP/M and programming into EPROM 

MEM-99520K (KIT) $175.95 

MEM-99520A (A&T) $225.95 



S D SYSTEMS 

EXPANDOPROM 

\EXPANDABLE TO 32K USING 2716 EPROMS 




S-100 bus compatible, uses 2708 or 2716 EPROMs 
Dip switches allow selection of : each EPROM, 16K 
or 32K boundary, wait states 

MEM-32220K (KIT) $149.95 

. MEM-32220A (A&T) $199.95 



GET THE INSIDE TRACK 

JADE DOUBLE-D 

DOUBLE DENSITY DISK CONTROLLER 

Read/write single or double density, 8" or 5'/ 4 "drives 

On board Z-80 insures reliable operation 

CP/M compatible in either single or double density 

Density is software selectable 

Up to 4 single or double sided, single or double 

density drives may be mixed on the same system 

EIA level serial printer interface on board-up to 9600 

baud (perfect for despooling operations) 

All the hard work of disk access is done by the on 

board Z-80A and 2K memory, leaving your host 

CPU free for its normal duties 

Uses IBM standard formats for proven reliability 

THIS BOARD REALLY WORKS mill 

IOD-1200K (DOUBLE-D KIT) $285.00 

IOD-1200A (DOUBLE-D A&T) $349.00 

IOD-1200O (MANUAL ONLY) $15.00 

S D SYSTEMS 

VERSAFLOPPY II 

DOUBLE DENSITY DISK CONTROLLER 




Single or double density floppy disk controller 

985600 bytes on 8" double sided diskettes 

259840 bytes on double sided 5%" diskettes 

S-100 bus (IEEE) standard compatible 

IBM 3740 format in single density 

8" and 5 1 / 4 " drives controlled simultaneously 

Operates with Z-80, 8080, and 8085 CPU's 

Controls up to 4 drives 

Vectored interrupt operation optional 

IOD-1160K (KIT) $335.95 

IOD-1169A (A&T) $385.95 



S D SYSTEMS 

VERSAFLOPPY 

VERSATILE FLOPPY DISK CONTROLLER 




IBM 3740 soft sectored format 

S-100 Z-80 or 8080 compatible 

Controls up to 4 single or double sided drives 

Compatible with all popular disk drives 

CP/M compatible 

Listings for control software included 

IOD-1150K (KIT) $189.95 

IOD-1150A (A&T) $239.95 



NEW 2 OR 4 MHz REV. C BOARD 

THE JADE BIG Z 

Z-80 CPU BOARD WITH SERIAL I/O PORT 
2 or 4 MHz switchable, on-board 2708, 271 6, or 2732 
EPROM useable in SHADOW mode (full 64K RAM) 
Automatic MWRITE generation if no front panel 
On-board USART for sync or async RS232 

CPU-30201K (KIT) $159.00 

CPU-30201 A (A&T) $209.00 



S>U£ 



S D SYSTEMS 

EXPANDORAM II 

4 MHz RAM BOARD EXPANDABLE TO 2S6K 




S-100 bus compatible, up to 4 MHz operation 

Expandable memory from 16K to 256K 

Dip switch selectable boundaries 

Page-mode allows up to 8 boards on the same bus 

Invisible refresh; PHANTOM output disable 

Designed to operate in Z-80 based systems 

MEM-16631K (16K KIT) $295.95 

MEM-16631 A (16K A&T) $345.95 

MEM-32632K (32K KIT) $369.95 

MEM-32632A (32K A&T) $419.95 

MEM-48632K (48K KIT) $444.95 

MEM-48632A (48K A&T) $494.95 

MEM-64632K (64K KIT) $519.95 

MEM-64632A (64K A&T) $569.95 

S D SYSTEMS 

VDB-8024 

80 X 24 I/O MAPPED VIDEO BOARD 




80 character by 24 line display, 7X10 dot matrix 
Composite or seperate TTL video outputs 
On-board keyboard interface with power 
On-board Z-80 and 2K RAM 
Blink, underline, reverse, protect, up/down scroll 
Upper/lower case characters, 32 special characters 
Optional 128 user-programmable characters 

IOV-1020K (KIT) $329.95 

IOV-1020A (A&T) $389.95 



S D SYSTEMS 

SBC-1 00/200 



2 OR 4 MHz SINGLE BOARD COMPUTER 




S-100 bus compatible Z-80 CPU 

1K of on-board RAM 

4 EPROM sockets accomodates 2708, 2716, or 2732 

One parallel and one serial I/O port 

4-channel counter timer chip (Z-80 CTC) 

Software programmable serial baud rates 

CPC-30100K (2 MHz KIT) $249.95 

CPC-30100A (2 MHz A&T) $299.95 

CPC-30200K (4 MHz KIT) $289.95 

CPC-30200A (4 MHz A&T) $339.95 



250 BYTE February 1980 



PRICES SLASHED FOR FEBRUARY ! 

CALL TOLL-FREE AND SAVE 

800-421-5809 CONTINENTAL U.S. 800-262-1710 INSIDE CALIFORNIA 



S D SYSTEMS 

IZ-80 STARTER KIT 

COMPLETE Z-80 MICROCOMPUTER 




On-board keyboard, display, EPROM programmer, 

and cassette interface 

On-board S-1Q0 interface 

Wire-wrap area and room for 2 S-100 connectors 

Two 8-bit parallel' I/O ports, 4-channel CTC, 5 

programmable breakpoints 

Examine and change memory, I/O ports, or register 

CPS-30010K (KIT) $279.95 

CPS-30010A (A&T) $349.95 

CP/M 2.0 

Digital Research has done it again! This new release of their 
industry standard disk operating system is bound to be an 
even bigger hit than the original version. All of the 
fundamental file-size restrictions of release 1 have been 
eliminated, while maintaining full compatibility with the 
earlier versions. This new release can be field-configured by 
the user for a single mini-disk up through a multiple drive 
hard-disk system with 128 megabyte capacity. Field 
configuration can be accomplished easily through use of the 
Macro Library (DISKDEF) provided with CP/M 2.0. 

A powerful operating system for only . . . $150.00 

JADE'S NEW MOTHERBOARDS 

THE ISO-BUS 

WERE PROUD OF OUR MOTHER I 

6-SLOT 

BARE BOARD $24.95 

KIT $49.95 

ASSEMBLED & TESTED $59.95 

12-SLOT 

BARE BOARD $39.95 

KIT $89.95 

ASSEMBLED & TESTED $99.95 

18-SLOT 

BARE BOARD $59.95 

KIT $129.95 

ASSEMBLED & TESTED $149.95 

SPECIAL PACKAGE PRICE 

IROCKWELL AIM-65 

\THE HEAD-START IN MICROCOMPUTERS 

lKIM-1 compatible 
Ion-board printer 
IfuII ACSII keyboard 

AIM-65 W/1K RAM..$375.00 JQp^SiiPJBjl 
AIM-65 w/4K RAM..$450.00iMM. — » ■-- * ISf 
8K BASIC ROM..$100.00 " 
POWER SUPPLY..$59.95/ 
CASE for AIM-65..$49.95_ 
| 4K Assembler/Edltor..$80.0<T 

Special Package Price $599.00 

4K AIM-65. 8K BASIC ROM, Power Supply, and Case. 




JADE 
MEMORY EXP